Hostile Mobs are only spawning from spawners and very rarely naturally.

I can stand outside all night and maybe see one mob at all, with the exception of phantoms which spawn correctly. I can't hardly find any creepers, zombies, witches, spiders, or skeletons.

I'm not sure how to replicate it on a different world, but I would like to attach my savegame so you can take a look, but it is over 300mb and it won't let me upload it b/c it is too big.

Thanks in advance and let me know if there is any other information you need.