Sometimes when loading a world all mobs are teleported one block either horizontally or diagonally, often into solid blocks.

Affects versions1.7+

Sometimes when loading a world all mobs are teleported one block either horizontally or diagonally, often into solid blocks. This issue seems more regular in worlds that have few blocks (e.g. sky block)(but i have had it occur on an amplified world) and more regularly in older versions (though i have found it happen twice in a 1.8.7 and 1.8.8 world). Chickens seem to be particularly susceptible and tend to be teleported to the centre of the adjacent blocks (killing them rather quickly). ALL LOADED MOBS are moved in the same direction (haven't been able to replicate with armour stands yet though) Cows and sheep seem to right themselves after a few tics and generally don't die. But for thiner mobs such as skeletons and chickens it is normally fatal. This is generally accompanied by a short lagspike. Mobs can also be teleported into non solid blocks or air this way.(allowing sheep to escape fences.

to test this i would suggest putting 10 chickens in a 1 by 1 by 2 hole in an all air world and saving ,quitting mine craft and re-opening it 10 times.

(this whole thing may just be a symptom of a struggling RAM so please also test with a low dedicated RAM)

I couldn't get any pictures as this happens as soon as you load the world so it is borderline impossible to capture.