Villagers Disappear

After running the server for sometime, villagers will continually disappear.

Setup:

1. A small village with 8-10 villagers in a gigantic wall.

2. Monsters spawning turned off.

3. All beds are in houses with 4 block high ceilings.

4. No escape. Two iron doors. Those doors are not even functional, as I use command blocks to teleport @p (nearest player) when within a radius of 1 next to the door.

5. Villagers are upgraded to either Expert or Master.

6. Villagers have custom names.

Observations:

1.  When a villager disappears, their job site block appears to be locked as if they were still alive - locked as in, a newly spawned villager will not occupy it, I must first destroy the block and recreate for it to be claimable.

2. I have noticed a change in behavior with some of the villagers before they went missing; for example, one seemed to always stand outside of the house containing his job site block. It is strange as they behaved normally sometime before (visiting jobsite block, sleeping, etc.)

3. I use /tp @e[type=villager] @s to confirm which villagers are gone.

4. I keep having to recreate one profession only for another to disappear hours later.

Lastly, in a desperate attempt to stop this from happening, I tried making all villagers invulnerable, and they have still been disappearing.

I've been experiencing this over a week's time. I was hoping the Bedrock Server upgrade to 1.14.20.1 would fix the issue, but it has persisted.