No Mobs spawning

[PaulHotel]

No mobs are spawning in my world l. I am in normal mode or hard

[Kalbintion]

There is a hard-coded mob cap of the world, if you fly around a lot or have mob grinders setup, this cap can easily be hit within seconds. Typing /cofh killall can remove mobs that are otherwise taking the mob cap. You can visit the minecraft wiki about mob spawning to see additional information about spawn caps.