So I have been attempting to kill some bosses duo and it seems quite a few of the mobs are immune to Rapture including Korocust, the Protector, and Emperor Chottal.
Checking mqemulator it seems that only the protector should be so immune:
http://mqemulator.net/npc.php?id=89144
http://mqemulator.net/npc.php?id=89001
http://mqemulator.net/npc.php?id=103219
What source are you using to flag charm/mez immunity? I googled decently but I wasn't able to find anything on rapture immunity for Korocust or Chottal, but perhaps I'm looking in the wrong places.