Sometimes my donkey disappear when I get off my donkey in survival mode

As title, not due to I get lost my way cause my donkey disappeared, sometime I get off my donkey, my donkey will disappeared immediately, and maybe come back at original place after 1, 2 minecraft days or not.

 

My minecraft version is 1.14.2 and no install any mod, please help to reserve this issue, and I can provide some trail what you need in my capability range.

 

Thank you !!