There's two ways this can occur, normally via the thaumcraft way or not being able to get a "good" connection. But a way to solve this is to either get a better connection or get some sort of AOE murder all things in a 20 meter radious
I am using Optifine and I am 100% sure that Optifine isn't causing it. WAILA nor radar show those mobs. Neither of those is affected by Optifine (Saw it with those crop sticks).
just humor me as like i say optifine messes with base class it is possible that optifine is messing with things and map cant render it not 100% though who has had it that doesnt use optifine
From what I have found out this is a desynchronization there isn't much I can do about it the main issue once again from research is Minecraft networking system which I'd interesting at best