Mobs (animals) randomly despawning

Mobs (animals) that are tied to a fence by a lead are randomly despawning starting with 1.13.0.1 Beta. You can find the video I did about the bug here: https://youtu.be/mQcITINOxDU . The horse was tagged.

As I streamed every day you can actually see it happening:

https://www.twitch.tv/videos/444598882 v1.12.0.14 Beta - 26-06 - at 1:25:20 you can clearly see me taking the horse near the waterfall; If you pause at 1:25:28 you can see the llamas and the sheep in the wool farm and a pen full of cows

https://www.twitch.tv/videos/445080542 v1.13.0.1 Beta - 27-06 - all stream was inside the base

https://www.twitch.tv/videos/445503592 v1.13.0.1 Beta - 28-06 - min 10:12 - the cows are by the waterfall, the horse is not; 12:44 - the purple sheep is there (by the old base); 20:40 - realisation (I was missing my horse); 58:44 - the purple sheep is missing, also a llama dissapeared; 1:02:00 - the cows by the waterfall dissapeared