mobs doesnt spawn

[KafeIek]

when i was exploring my world it was announced that mob captain just spawned, i saw purple particles just like chat message but there was no mob. The only other mob mod i have installed is mobs improve over time

[PuckiSilver]

What Minecraft version are you in?

Other mods may very well mess with it but if the message appeared and the particles appeared, the mob very likely did spawn - maybe you didn’t find it because it was underground? Or it despawned before you got there? (That last thing is only possible in older versions)