Villager just won’t change profession

I wait until the time is between 2000 and 9000, but I can’t change the profession. The villager has full access to their bench, which in my case was a Lectern, but it just won’t change it’s profession.

The villager can also access his own bed. The villager won’t change from Librarian no matter what I give it. I already tried Composter but no change. Brewing stand, same, no change.

I just want to keep switching him from Librarian to nothing so I can get much needed Mending books which I have had no luck with so far and the closest village to me is pretty far away and tedious to move villagers, even though the villager in question is just near my house.

Sorry if this is worded a bit strangely but I’m having a tough time understanding everything about these new villagers and stuff. If it helps, I have been trading with him a lot for emeralds and right now, the villager is an Expert, so could that be why it isn’t changing?