The default round time (5 minutes) for the following maps is not long enough to complete them, so if humans survive long enough the round just ends before the end of the map can even be reached. Admins can manually extend the time, but if there aren't any on or they don't know how, it's impossible to complete these maps.

ze_saw_final
ze_Portal_Story_v3_1 (I haven't played this one in weeks, so it may have already been increased?)
ze_accelerator_escape_new

8-9 minutes should probably be enough for saw and portal story, accelerator is really long so it'll probably need more like 10.