Mobs standing around after update

All my Cows and Sheeps are just standing around and only rotating on their own axis.
this is only on my server, if i start a local game in creative mode sheeps and cows walk around and behave normal.
if i use wheat, all sheeps will immediatly follow me but if i held another block, they will get stuck just like before.
the problem will occur in survial as also in creative mode.