I've noticed recently that my chickens get stuck in the corners of fences. It doesn't matter if it's wood or stone. Sometimes two chickens will get stuck in the same corner and are unable to move from their spot. At some point, the chickens will escape.
I've been finding my animals in other pens they did not start in, or not in their pen at all. Which I assume is due to clipping though.
Though this isn't a major issue, it's a little annoying.