(Reported to helpshift - added here for ease of reference)
Several enemies in caves spawn far later than they should - like long after the player has gone past and fought other enemies -
So far - the crocodile in the middle passage in Gallaman’s Tomb just before the final chamber - only spawns after you’ve already pulled the first few crocs from the final room.
Many of the spiders in Weaver’s Hollow and Scuttler’s Shortcut - too many to list, several seem to never spawn at all
The crafters in the first chamber of Sinner’s Refuge and the dancers in the final chamber. Also appears to be a problem with the ‘Chosen of Asura’ spawn, but that needs more investigation.
The missing spawns in Sinners Refuge confirmed by @Kanza1 as also happening on Official Servers, including no one spawning at the ‘Chosen of Asura’ spot until waiting through a full respawn cycle.