So, this is the weird bug that I have for a long time ago.
For some reason, the last player who connect to the server could not see the chat messages (except for the info ones) at all, but they can still send messages and the rest of the server can actually read them.
I tried searching in google and in this forum for some info, but sadly it seems that nobody else has this kind of issue (I read that someone couldn't see the chat while in spec, but this glitch happens even if the player is actually playing in a team).
Also, this only happens to the last user who connected to the server. It doesn't matter how many slots the server has (in the beginning the server had 16 slots, then 24, and now 18, and the bug only happened in the latest slot), but strangely enough, it doesn't happen every time, but if you're unlucky, you have to wait until someone leaves the server and then use the retry command for recovering the chat.
Also also, the unlucky user just cannot see user messages, while the server ones (AKA Advertisements, command responses, plugin information) work just perfect. Also, the player can play just normal, there is no lag, no sounds glitching/lagging, nothing.
Here is my server plugins list:
Spoiler
[SM] Listing 199 plugins:
001 "Admin File Reader" (1.10.0.6502) by AlliedModders LLC
002 "Admin Help" (1.10.0.6502) by AlliedModders LLC
003 "Admin Menu" (1.10.0.6502) by AlliedModders LLC
004 "Admin Smite" (2.1) by Hipster
005 "Advanced Rules Menu" (3.3) by Russian JP, Eyal282
006 "Advertisements" (2.1.0) by Tsunami
007 "AFK Manager" (4.3.0) by Rothgar
008 "Anti-Flood" (1.10.0.6502) by AlliedModders LLC
009 "Anti-Ping Mask" (1.6.2M) by atom0s
010 "[TF2] Anti CCC Bugs" (1.0) by yelks
011 "TF2: Anti-Arena Latespawn (v from Mr_panica)" (1.0) by Mr_panica (code borrowed from [TF2] Ghost Mode)
012 "[TF2] Auto Kits" (0.1.0) by Classic
013 "Basic Chat" (1.10.0.6502) by AlliedModders LLC
014 "Basic Comm Control" (1.10.0.6502) by AlliedModders LLC
015 "Basic Commands" (1.10.0.6502) by AlliedModders LLC
016 "Basic Info Triggers" (1.10.0.6502) by AlliedModders LLC
017 "Basic Votes" (1.10.0.6502) by AlliedModders LLC
018 "[TF2] Colored Engineer Buildings" (1.1) by Oshizu
019 "[TF2] Building Hats" (2.0) by Pelipoika
020 "CallAdmin" (0.1.8) by Impact, dordnung
021 "CallAdmin UserManager" (0.1.8) by dordnung, Impact
022 "Change Team" (1.0.1) by MrSquid
023 "Chat-Processor" (2.2.3) by Drixevel
024 "[Any] Chat Logging Redux + RTF Support" (1.1.2) by McFlurry, Keith Warren (Shaders Allen)
025 "[TF2] Chester Spawner" (1.1) by TonyBaretta
026 "Client Preferences" (1.10.0.6502) by AlliedModders LLC
027 "Chat Processor - Simple Chat Processor Wrapper" (1.0.0) by Keith Warren (Shaders Allen)
028 "[Source 2013] Custom Chat Colors" (3.1.0 CP) by Dr. McKay, Fixed up by Keith Warren (Shaders Allen)
029 "Custom Chat Colors Menu" (2.1) by ReFlexPoison
030 "Discord API" (1.0) by .#Zipcore, Credits: Shavit, bara, ImACow and Phire
031 "Discord: CallAdmin" (1.1) by .#Zipcore
032 "Discord: SourceBans" (1.0) by .#Zipcore
033 "Discord: SourceComms" (1.1) by .#Zipcore
034 "[TF2/CS:GO?] Double Quote Fix" (18.0220.0) by Derek D. Howard
035 "[TF2] DSP Effects" (1.1.1) by A.I, Hurp Durp
036 "[TF2] Enhanced Item Notifications" (1.1.0) by Dr. McKay
037 "Fake Connect/Disconnect Messages" (1.0.0) by aIM
038 "Fun Commands" (1.10.0.6502) by AlliedModders LLC
039 "Fun Commands X" (2.5) by Spazman0 and Arg!
040 "Fun Votes" (1.10.0.6502) by AlliedModders LLC
041 "Godmode with Effects!" (1.0) by Twin_Future
042 "Teleport Player" (1.8) by Headline, Original: HyperKiLLeR
043 "LerpTracker" (0.8) by ProdigySim
044 "Light Colors" (0.6) by Jindo
045 "MapChooser Extended" (1.10.2) by Powerlord, Zuko, and AlliedModders LLC
046 "Map configs" (1.3) by Berni
047 "[TF2] Necromasher" (1.1) by Pelipoika
048 "Nextmap" (1.10.0.6502) by AlliedModders LLC
049 "Map Nominations" (1.10.0.6502) by AlliedModders LLC
050 "Player Commands" (1.10.0.6502) by AlliedModders LLC
051 "Player Ranks" (3.4.1) by Aderic
052 "Reserved Slots" (1.10.0.6502) by AlliedModders LLC
053 "Resize Players" (1.5.1) by 11530
054 "Player Respawn" (1.6) by Rogue
055 "Reconnector" (0x01) by Chdata
056 "Soldier Tribute Statue Spawner" (1.1) by Mr.Skullbeef, Russ
057 "Rock The Vote Extended" (1.10.0) by Powerlord and AlliedModders LLC
058 "Roll Giveaway" (1.1.1) by sim242, Russ
059 "Say Sounds (including Hybrid Edition)" (4.0.8) by Hell Phoenix|Naris|FernFerret|Uberman|psychonic|ed gecom|woody|Miraculix|gH0sTy
060 "SourceBans++: Admin Config Loader" (1.6.3) by AlliedModders LLC, SourceBans++ Dev Team
061 "SourceBans++: Bans Checker" (1.6.3) by psychonic, Ca$h Munny, SourceBans++ Dev Team
062 "SourceBans++: SourceComms" (1.6.3) by Alex, SourceBans++ Dev Team
063 "SourceBans++: Main Plugin" (1.6.5) by SourceBans Development Team, SourceBans++ Dev Team, Russ
064 "SourceBans++ Report Plugin" (1.6.3) by RumbleFrog, SourceBans++ Dev Team
065 "SourceBans++: SourceSleuth" (1.6.3) by ecca, SourceBans++ Dev Team
066 "Self-Mute" (1.0) by Otokiru
067 "Server Hud Logo" (2.2) by ReFlex
068 "SM File/Folder Downloader and Precacher" (1.4) by SWAT_88
069 "Evil Admin - Glow" (1.0.107) by <eVa>Dog
070 "Set Health" (1.2.2) by Mr. Blip
071 "SM warn" (1.2.5) by ecca, Russian
072 "Sound Commands" (1.10.0.6502) by AlliedModders LLC
073 "Super Spray Handler" (1.2.3) by shavit, Nican132, CptMoore, Lebson506th, and TheWreckingCrew6
074 "[Store] Math Credits" (1.2.9) by Arkarr, Russ
075 "[Store] Model Changer" (1.1.4) by Russian JP, FlaminSarge (based on Damizean's TF2 Equipment Manager)
076 "[Store] NadeTrails" (1.1-alpha) by Phault
077 "[Store] Titles" (1.1-alpha) by alongub
078 "[Store] Trails" (1.1-alpha) by alongub
079 "[Store] Unusuals" (1.0) by Russ
080 "[Store] Weapon Colors" (1.1-beta) by Phault
081 "[Store] Core Module" (1.3.1 dev0) by Alongub, Keith Warren(Drixevel), Arrow768, Russ
082 "[Store] Distributor Module" (1.3.0 dev1) by Alongub, Keith Warren(Drixevel), Arrow768
083 "[Store] Gifting Module" (1.3.1 dev0) by Alongub, Keith Warren(Drixevel), Arrow768, Russ
084 "[Store] Inventory Module" (1.3.1 dev0) by Alongub, Keith Warren(Drixevel), Arrow768, Russ
085 "[Store] Loadouts Module" (1.3.0 dev1) by Alongub, Keith Warren(Drixevel), Arrow768
086 "[Store] Logging Module" (1.3.0 dev1) by Alongub, Keith Warren(Drixevel), Arrow768
087 "[Store] Refunds Module" (1.3.0 dev1) by Alongub, Keith Warren(Drixevel), Arrow768
088 "[Store] Shop Module" (1.3.1 dev0) by Alongub, Keith Warren(Drixevel), Arrow768, Russ
089 "stuck" (1.3) by Erreur 500
090 "[TF2] Taunt Speed Modifier" (2.2) by Tak (Chaosxk)
091 "[TF2] TF2Attributes" (1.3.2) by FlaminSarge
092 "TF2IDB" (0.93) by Bottiger
093 "TF2 Set Class" (1.2.2) by Tylerst
094 "TF2 Taunts TF2IDB" (1.6.3.66-tf2idb) by fakuivan
095 "[TF2] Econ Data" (0.17.1) by nosoop
096 "[Tf2] Third Person Cookies!" (1.3.6) by Friagram, Russ
097 "Thriller" (0.2) by linux_lover
098 "Tidy Chat" (0.5) by linux_lover
099 "Timescale Windows Fix" (1.0.0) by Bakugo
100 "[ANY] Unrestricted FOV" (1.2.0) by Dr. McKay
101 "Web Shortcuts" (1.1) by Kyle Sanderson, Nicholas Hastings
102 "Aim Names" (0.8) by -MCG-Retsam & Antithasys
103 "Pyro Taunt Street Fighter" (1.2) by TonyBaretta
104 "Pyro Taunt Energy Ball" (1.2Spell) by TonyBaretta
105 "Very Basic High Ping Kicker" (1.4) by msleeper
106 "The Amplifier" (2.4) by RainBolt Dash (plugin); Jumento M.D. (idea & model); Naris and FlaminSarge (helpers)
107 "TF2 Class Restrictions" (0.6.1) by Tsunami
108 "[TF2] Bonk" (1.0) by Walgrim
109 "[TF2] Engineer Pads" (1.1.0) by Starblaster 64
110 "Panzer Tank Rockets" (0.2.1) by AI
111 "Freak Fortress 2" (Unofficial 1.19.9) by Many many people
112 "WWA: 2R Abilities" (1.10.4) by Russian JP
113 "Freak Fortress 2: Bloodrider - the 9 Soul Grenade Spammer" (3.0) by M7
114 "Freak Fortress 2: Koishi's Abilities Pack" (1.23) by Koishi (SHADoW NiNE TR3S)
115 "FF2: Coffin Demoman Abilities" (1.1.5) by Russian JP
116 "Freak Fortress 2: Default Abilities" (1.10.4) by RainBolt Dash
117 "Freak Fortress 2: Default DOTs" (1.1.3) by sarysa
118 "Demopan is nerfed" (1.0.0) by JP Russian
119 "FF2: Abilities for Monika" (1.0) by M7
120 "Freak Fortress 2: DOT Template" (1.0.0) by sarysa
121 "Freak Fortress 2: Abilities for Double" (2.0) by M7
122 "Freak Fortress 2: Drain Over Time Platform" (1.1.0) by sarysa
123 "freaks\duck_abilities.ff2"
124 "Freak Fortress 2: Easter Abilities" (1.10.7) by Powerlord and FlaminSarge, updated by Wliu
125 "FF2 Package - Mokou + Radigan Conagher" by EP
126 "Freak Fortress 2: Abilities of 1st set" (1.10.7) by RainBolt Dash
127 "Freak Fortress 2: Advanced Formulas" (1.0) by Batfoxkid
128 "Freak Fortress 2: Block Item/PowerUp dropping" (1.0) by Naydef
129 "Freak Fortress 2: Body Effects" (1.2) by Deathreus
130 "Freak Fortress 2: Bombinomicon" (1.0) by Deathreus
131 "Freak Fortress 2: Boss Tweaks" (1.0) by frog
132 "Freak Fortress 2: Cast a Projectile" (1.0.0) by J0BL3SS
133 "Freak Fortress 2: Completely Stripped Version of Darth's Ability Pack Fix" (1.2) by Darthmule, edit by Deathreus
134 "Freak Fortress 2: Deathreus Boss Pack" (1.5) by Deathreus
135 "Freak Fortress 2: AMS Do Ability" (1.1.0) by Batfoxkid
136 "Freak Fortress 2: Dynamic Defaults" (1.3.2) by sarysa, with a small amount of code by RainBolt Dash
137 "[TF2] Freak Fortress 2: Fall Effects" (0.4) by Naydef
138 "Freak Fortress 2: Fog Effects" (1.02) by Koishi
139 "Freak Fortress 2: Frozen Abilities for Elsa and Olaf" (1.0) by SHADoWNiNETR3S
140 "Freak Fortress 2: Almighty Push / Universal Pull" (1.1) by SHADOW93 | Waka Flocka Flame (base code by Friagram)
141 "Freak Fortress 2: Grapple Hook Plus" (1.4) by kking117
142 "Freak Fortress 2: Pull" (1.0.0) by Blinx
143 "Freak Fortress 2: Move Speed" (1.3.4) by SHADoW NiNE TR3S
144 "Freak Fortress 2: Saxtoner Ability Pack" (1.6.6) by Otokiru, updated by SHADow93
145 "Freak Fortress 2: WC3 Ability Pack" (1.2.4) by Otokiru, SHADoW NiNE TR3S
146 "Freak Fortress 2: Phat Rages" (0.9.5) by frog,Kemsan,Peace Maker,LeGone,RainBolt Dash
147 "Freak Fortress 2: Rage Model" (1.1) by frog
148 "Freak Fortress 2: Replace Projectile" (1.0.2) by frog, friagram
149 "Freak Fortress 2: Salmon Summon System" (0.4.6) by Koishi (SHADoW NiNE TR3S)
150 "Freak Fortress 2: Salmon Summon System" (0.4.6) by Koishi (SHADoW NiNE TR3S)
151 "Freak Fortress 2: sarysa's mods, second pack" (1.1.1) by sarysa
152 "Freak Fortress 2: sarysa's mods, third pack" (1.1.1) by sarysa
153 "Freak Fortress 2: sarysa's mods, fourth pack" (1.4.2) by sarysa
154 "Freak Fortress 2: sarysa's mods, fifth pack" (1.1.1) by sarysa
155 "Freak Fortress 2: sarysa's mods, seventh pack" (1.3.1) by sarysa
156 "Freak Fortress 2: sarysa's mods, eighth pack" (1.2.3) by sarysa
157 "Freak Fortress 2: sarysa's public mods, first pack (ROTT boss)" (1.1.0) by sarysa
158 "Freak Fortress 2: sarysa's public mods, second pack" (1.0.2) by sarysa
159 "Freak Fortress 2: sarysa's public mods, third pack" (1.0.1) by sarysa
160 "Freak Fortress 2: sarysa's public mods, third pack" (1.0.2 BBG) by sarysa
161 "Freak Fortress 2: ServerCommandRage" (1.1) by frog
162 "Freak Fortress 2: TFConditions" (1.1.1) by SHADoW NiNE TR3S
163 "Freak Fortress 2: Timed Weapon Rage" (1.0) by Deathreus
164 "Freak Fortress 2: The Witch Doctor" (1.0) by Deathreus
165 "Freak Fortress 2: The Blitzkrieg Return" (0.1.0) by Batfoxkid
166 "Unofficial Freak Fortress 2: Defaults" (0.6.0) by Many many people
167 "Freak Fortress 2: Menu Abilities" (1.0.0) by Batfoxkid
168 "Freak Fortress 2: Gray Mann" (1.4.3) by SHADoW NiNE TR3S, edited by Batfoxkid
169 "Freak Fortress 2: Bat's Public Pack" (1.9.0) by Batfoxkid
170 "Freedom Abilities" (2.0.0) by WildCard65
171 "Freak Fortress 2: Halloween 2013 Boss Pack" (1.3) by Friagram
172 "Freak Fortress 2: Boss Framework" by Friagram
173 "Freak Fortress 2: Improved Saxton" (1.0.5) by sarysa
174 "Devilrune: Jevil Abilities" (2.0.5) by Russian JP
175 "TGW: Jojo Engi Abilities" (1.1.5) by Russian JP
176 "Freak Fortress 2: Killing Floor Abilities" (2.0) by M7
177 "FF2: Killing Mann Change Theme on Lifelose" (1.0) by M7
178 "Freak Fortress 2: New Abilities" (2.0.0) by M7
179 "Freak Fortress 2: M7's new Abilities" (3.0) by M76030
180 "FF2 Ability: Customazible Clipless Weapons" by M7
181 "Freak Fortress 2: Misc Stuff" (5.0) by M7
182 "Abilities for Shadow the Edgehoge" (1.5) by M7
183 "Freak Fortress 2: PayDay Abilities" (1.0) by M7
184 "Freak Fortress 2: Boss Item Pickup" (1.0) by Friagram
185 "Freak Fortress 2: Powerlord Abilities" (1.0) by Powerlord
186 "Freak Fortress 2: rage_overlay" (1.9.2) by Jery0987, RainBolt Dash
187 "Freak Fortress 2: Russian Abilities" (1.2.0) by Russian JP
188 "Freak Fortress 2: Lives Abilities" (1.0.5) by Russian JP (AKA: JPZV)
189 "Freak Fortress 2: Beepman's Abilities" (1.3) by 93SHADoW
190 "Freak Fortress 2: The Blitzkrieg" (3.3 Beta (Stable)) by SHADoW NiNE TR3S, sarysa
191 "Freak Fortress 2: Gray Mann" (1.0) by SHADoW NiNE TR3S
192 "Freak Fortress 2: Koishi's Abilities Pack" (1.23) by Koishi (SHADoW NiNE TR3S)
193 "Freak Fortress 2: Koishi's Boss Abilities" (1.23) by Koishi (SHADoW NiNE TR3S)
194 "Freak Fortress 2: skeleton king" (1.0.1) by DaNetNavern0
195 "WWA: Soldier Otaco Abilities" (1.10.4) by Russian JP
196 "Freak Fortress 2: Overlay Rage for AMS" (1.0.0) by M76030
197 "Freak Fortress 2: special_noanims" (1.10.7) by RainBolt Dash, Wliu
198 "Freak Fortress 2: The Killing Manns abilities" (1.0) by M7
199 "Freak Fortress 2: The Administrator" (1.0) by M7