I've made a classic mob farm using a zombie spawner in 1.11 and whenever I get 30+ mobs in my drop zone they just die when new ones come in, it's like they're crushing each other.
Is there any way to fix this? The water doesn't work, an extra drop layer using a piston doesn't work either.
Height doesn't matter, they die anyway if there's more than 30ish I Cant idle this way for XP anymore.