I'm having a frustrating bug that's causing villagers to disappear for extended periods of time.
The way I've encountered this bug is after enclosing a villager with good trades in a structure where they won't be able to escape (Shown in photo). Upon leaving and coming back to the world/chunk the villager may not be there, and a strange effect is activated when this happens.
Originally I thought the villager died because I thought a baby zombie entered the 1x1 hole and killed the villager. But after 3 world reloads the villager somehow managed to reappear. Before the villager reappeared,the strange effect was that in he 1x2 space the villager was standing in, you won't be able to place any blocks there, the block instantly disappears upon placement. However, upon reloading the world the blocks you placed will be back in your inventory.

RECREATION:

1. Place a villager in a 2 block high or a 3 block high enclosure where they won't be able to escape 
2. Keep opening and exiting the world, it'll eventually happen after enough loads

EFFECTS:

1. Unable to place blocks in the 2 block space the villager was standing in.
2. Villagers will retain any potion effects that were applied before their disappearance,(the fire protection potion was applied roughly 2 hours before they disappeared) as if they were never gone.