This only happens in the 1.19+ versions, in 1.18.2 works fine.
Whenever I create a new world with alex's mobs and citadel, the datapacks tab says that "alexmobs resources" is incompatible and that it was made for an older version, despite the fact that I am playing the most recent forge version with the most recent alex's mobs file for that version. When I create the world, there are a lot of mobs from the mod missing, and structures like the leafcutter anthill don't generate. I have tried reinstalling the mod, deleting the config folder so that it is created again with default settings, trying different forge versions, but it keeps happening. However, when I create a server on another webpage, for example aternos, and use the exact same forge and alex's mobs version I was using, it generates/spawns everything properly.

i've been having the same problem :/ tried the same troubleshooting methods and none have worked for me either