Sometimes my mount just disappear after i get a random lag spike when i dismount and cannot see it again til i reloaded my world (there was one instance that my mount permanently disappeared in the nether).

Animals that got leashed sometimes just get lagged while im traveling with them and got detached, maybe this is just a lag but i dont remember this happening in previous versions. This is very annoying because it could greatly slow me down in my travel or may even lose my mount without me knowing.