Villager will not assign itself to a job site block

I have been removing and replacing a lectern in a house with only one villager in an attempt to get a villager with a mending book trade. But after 4 or 5 times of removing and replacing the lectern, the villager has become unemployed and will not assign itself to the lectern and is staying unemployed. There are no other job site blocks inside of the house because I removed all of them. Before this problem started, the villager would become unemployed when I removed the lectern and become a librarian again when I put it back. Is there anything I can do to avoid this problem? I am experiencing this problem in Bedrock Edition version 1.14.60