At first I thought my mobs were just escaping because I found it weird how my horses, sheep, chicken, and cows all started disappearing from my base so I made sure that my animal farm is tightly secured so that they have no chance of escape, however, they still manage to disappear and without a trace. One of my horses which I leashed onto a fence also disappeared while  its lead is still placed onto the fenced but it is not connected to the horse or anything. It also might be responsible for the disappearance of two elder guardian in one of the monuments we visited which only contained one elder guardian out of the supposed three.

Looking at this bug it seems that it affects other  types of entities as well  as it also affected my chests, item frames, dropper, dispenser. The chests were invisible and you couldn't access them and if you broke it you wouldn't get any item other than a chest. The droppers were visible but I couldn't access them same with the dispenser. The item frames were there but their content is missing and I couldn't retrieve them. Looking at this bug I think this was also responsible for the disappearance of my minecart with chest which disappeared a previously.

Please Fix