This is a minor bug involving entities spinning in water. It is easy to resolve but occurs somewhat frequently and can break immersion.

I have often found that when entering a village I will find a villager spinning uncontrollably in the water. I have also seen this affect untamed cats so I assume it would affect all entities. When I find the entity in question it is found swimming over a patch of seagrass of any length, as long as the entity in question makes contact with it. 

When pushed the entity will seek to return to the same location, but won't spin. if the entity is pushed out of the water the seagrass is growing in the bug will resolve. It looks like the entity is targeting the centre of the block the seagrass is growing on, and its pathfinding is causing it to spin. this would explain why the entity will always return to the location as long as it is able to swim directly there. 

I am unsure how exactly to reproduce it as I haven't seen the bug begin onscreen