Animals in pens and buildings disappearing

All animals keep disappearing. This has happened 4 times now since playing on the spooky mansion seed. I spend days building barns and pens, collecting animals just to have them all go poof. I have lost several really good horses that have been named and have saddles and armor on them. Nothing I do seems to fix this. This is very frustrating as it takes a fair bit of time to keep collecting animals. I am playing in survival with no cheats. Friends that have animals away from my current location don't lose their animals when this happens. Only the animals in close proximity to me seem to disappear.

Thank you, Jkraw88