Horses and boats despawn when I quit while riding/sitting in them

The title says it all.

I never had this issue before until yesterday, when my friend disconnected. When he came back his horse was gone, and today we were in boats. We both quit while in them and when we came back, the boats were gone and so were the horses in the boats. My friend is on XBOX One and I'm on PC.

This isn't a realm, it's my own local world. Somebody please help.

Thanks,

Chris