I have a underground base with villagers in them, I have 4 composters and 6 Villagers, if a Villager that's already a farmer goes to an upper part of my base (above the composter) he doesn't lose his job, but one of the unemployed villagers turns into a Farmer. Once the first farmer returns to his profession block, both stay farmers for the same block.

Also breaking the profession block doesn't seem to cause them to lose their jobs when this happens.

This issue also seems to mess with villagers AI or a problem in their AI cause this, cause some of them won't sleep nor go to they profession block when having to work. Also do they seem the get "stuck" in random spots until I open or break a door/block.

As seen in the images, 6 farmers yet only 4 composters.