I had this problem since I started playing this update (1.14.1+). I thougth that it was a problem with villagers wandering too far and other villagers claiming their workstation because i had only 3 composters in a village but more than 6 farmer villagers.

It seems I was mistaken, because today, playing 1.14.2 as I was making a trading hall, I encountered several problems:

1-Villager claiming a workstation far away in my basement
2-As seen in the picture, a second villager claiming the same workstation having another avaiable.

EDIT: Also when moving a leveled up villager to another place, even giving him the proper workstation he sometimes doesn´t claim it, even destroying the workstation and placing it again seems to do this. I think he may be trying to claim a workstation from other profession rendering him unable to restock or work.