Seem like there is still an issue with running workshop map collections, so I made this perl script that I use with the LGSM to let me automate running my workshop map collection on my server, perhaps it can help someone until running workshop map collections is "fully" supported:
https://github.com/Pintuzoft/OSWorkShopFix
Basically its just a serverscript written in perl, it parses the cs2server-console.log file looking for the end of a match, and if it finds it it will use ./cs2server send command and send the ds_workshop_changelevel command to the server with a random available map. the script will query the server for a list of maps which it keeps in memory until it needs it.
Its very simple, its not a plugin, I made it for my Linux server running LGSM, but perhaps it can help someone who wants to run a workshop map collection on their server to actually do that.
There is no voting etc it just randomizes the maps in the map collection the server has loaded.
./Pintuz