I heal two zombie villager white in easy mode in survival to populate my created village, there are also 3 beds, composter, fletching table and brewing stand to change their proffesions. But instead of breeding after a several days, when i open minecraft again, one of them is gone now after several days again, its totally gone. But there a fence on it. It's is a bug?
Could your villagers have had an accident? My villagers are accident-prone, and all my villages are naturally-generated ones that have dangerous drops. After losing several villagers who fell to their death I have learned to secure danger spots with fencing so that villagers can only traverse approved safe paths. I doubt that this is the case with your village since you planned and created it yourself, but don‘t over-estimate the intelligence of villagers.
Your villagers may be suffocating by glitching into a wall somewhere. I would consider this to be a bug. The only thing I can think of to prevent it would be to make sure the beds have room around them and the ceilings are at least three blocks high. If there are other possibilities I would like to know. In one of my villages three of my tamed cats died in one playing session and I have no idea how it happened. I only noticed an in-game notification that they had died.