No Spawns Unique to Nether Fortresses or Ocean Monuments

Seems like all the nether fortress and ocean monument spawns have completely ceased. No mobs like wither skeletons, blazes, or guardians seem to be able to spawn in this version. After last version's crazy fortress spawn rate, this is just weird. It seems like elder guardians are the only thing that can generate in new monuments, and only blazes that come from spawners can appear.