Named mobs randomly dying?

[Litos]

I run a private server for me and my friends. My friend named a bunch of sheep so they would not despawn for her barn build. For some reason the sheep have just started randomly dying. None of us have killed them and neither have our wolves and it looks like their pen has enough space so they don't get crushed. Is any one else experiencing this bug?

[Yojin]

Common bug im afraid, named mobs often clip into the floor somehow and die. Pretty sure it happens when they get loaded in, if you have any wolves you should check if they've taken damage. Don't think there's really anything you can do about it though