Villagers constantly disappearing in Minecraft Realms

we have two villages on our realms where the villagers seem to continually despawn/reset whenever all users have logged off the realm.

 

We have ruled out deaths due to zombies, drowned, pillagers, etc., as these are both fullly secured from mobs, (well-lit with torches, fully fenced and/or walled in, and essentially "zombie-proofed").

 

It is particularly frustrating to pay for Realms service so my friends and I can build up a shared world, only to have our Master Toolmaker or Master Butcher be reset multiple times per day.