About 1-2 times a week since the Nether update, my realm's settlement experiences mass despawning events. We have villagers, sheep, horses (tamed, leashed, and wild), cows and golems all disappear. Completely gone. These despawning events happen even when there's no way we've hit any sort of entity cap for the chunk. We've seen it despawn anywhere from 1-30 entities on our realm. 

This is super frustrating and demoralizing because it makes us lose huge amounts of progress. We've spent countless hours farming materials to trade and increase rep with villagers, only to have it be completely wiped out with no real obvious cause. Our town is 100% secure with really good lighting. They're just disappearing and we don't understand why.