Villagers getting stuck in water

Put the summary of the bug you're having here

What I expected to happen was...:
Villagers living their normal live

What actually happened was...:
Villagers getting stuck in water/unable to get out even tho stairs/slabs are placed to help and spinning furiously. After pushing them out of the water they get back in almost instantly and start spinning again. 

Steps to Reproduce:
I can't directly trigger it because they already do it on their own.