1.17.1 Wither Skeleton/Guardians not spawning

[Amun_Fortex]

I've noticed a bug that seems to be preventing Wither Skeletons and Guardians from spawning with minecraft forge installed. I have tried every version of forge for 1.17.1 (37.0.0 to 37.0.27) with no mods installed. I located a nether fortress and state for 30min with each instances and the only mobs that would spawn would be Blazes from the spawner itself, no skeletons or Wither Skeletons would be present at all. I then loaded a vanilla minecraft without forge and went to a nether fortress and within 4 minutes of being at the fortress 8 withers and a few normal skeletons spawned. I then went back to the modded version and double checked with a new world and the same result of nothing spawning happened. I traveled to the Ocean Monument and searched around only to find the bosses and cod would spawn. I've also tried other version of java ranging from jre-8u301x64, openJDK16Ux64 and older versions. 

I'm unsure as to what could be causing this and I'm up for running some more tests if there is anything I can help with. I'm also using CurseForge for my modded minecraft.