mp_roundtime is specified in seconds, so 5.3 seconds is a bit short for a round. You probably want 330 seconds instead.
Otherwise I can't see anything wrong with the infection time range. Try execute the config manually and check if the values were set properly:
Code:
exec sourcemod/zombiereloaded/zm_lila_panic_cs.cfg
zr_infect_spawntime_min
zr_infect_spawntime_max
If those are ok, I don't know. Could be timing issues with late configs so the infection timer is started before the map config file is executed.
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