Villagers Disappearing?

[JackThePhantom]

So I have a villager breeder and I built my trading hall under the breeder to make moving them convenient. Villagers wander the hall in between expansions. However after AFKing for a while waiting for the villagers to breed, the villagers already in the trading stations are gone for some reason. The area is well lit and there's more villagers wandering around so it can't be a zombie. The villagers are individually in their own stations so it can't be entity cramming. Not sure what's going on. I lost some fletchers with good arrow trades. Is there some feature erasing villagers when there's too many or is this a bug or what?

 

[JackThePhantom]

Also the entire area is claimed with default claim settings. The only people trusted on the claim I know in real life so it can't be them.