Mobs not spawning in Nether Fortress 1.17.1

[NaibuDeShinu]

As the title says, I have a forge server with the four of us playing hardcore. We ventured into the nether last night and cannot get the withers or any other mob to spawn in the area. We've found four other fortresses and checked the mob spawning and allow nether settings in the config file but still cannot get them to spawn. I loaded up vanilla minecraft 1.17.1 and it worked in the same world. I then removed all the mods and just tried forge 1.17.1 (37.1013) and the problem persists. Checking the debug menu we saw the correct amount of entities spawning in the area and only blazes spawned from their respective mob spawner. Not sure is this is a bug or if something is interfering on our end. Any insight would be appreciated.

[Tamas555255]

I have the same issue in singel player