Villager with trades locked gets unlinked to their workstation despite consistently working at it and restocking before, and an unemployed takes over the jobsite. This issue was also present in 1.14.30.

Steps to reproduce:

1. spawn in multiple villagers
2. give them beds to link to
3. place down one workstation
4. trade with villager linked to that workstation to lock trades

After an amount of game days, the villager with profession gets unlinked to their workstation, even with direct access to it. A new villager, previously unemployed, takes over the jobsite. The villager keeps its trades (as it is locked). 

In 1.14.30 or even earlier, the villager who gets unlinked may get linked to another workstation of a different profession (ex: librarian links to cauldron), although the workstation is already occupied by another villager. In that case, both villagers go work at the workstation, and both villagers keep their trades. I have not seen this bug after 1.14.60. (This issue has already been reported previously)

I am not sure if there are any other factors that effect this. The original villager never goes to its jobsite again (because it never restocks its trades). 

I have had this issue with fletchers, cartographers, librarians, masons, and clerics.