On our realm mine, my friends and a natural village's villagers keep disappearing. The first time was when we were both offline(Others may have been online) and we logged in and found over half our villagers missing. The second time was when we were both online but the chunks were unloaded and we go back and see another half (of the half left) had disappeared again.

Update: All my villagers have reappeared with exactly the same enchants...