Both me and my friend have encountered an odd bug affecting us in our Minecraft Realm. Sometimes, seemingly without a trigger, entities (including hostile mobs, friendly mobs, items, even my horse as I was riding it, and my friend) disappear. This happens every now and again - maybe in varying intervals of 10-60 minutes? 

I'm not too sure how to reproduce this bug as I have no idea what's causing it. 

Notably, disconnecting and reconnecting to the Realm fixes the bug until it pops up again later. 

I don't believe this is an issue with my internet or computer, since my friend has gotten it too, and my computer and internet are decent. 

EDIT: This was an optifine bug, oops.