I'm still seeing this in 1.15.2. If I replace the fences with 2-block high walls of dirt, the problem goes away, but the bees keep trying to pathfind through the fences to get back to their nest/hive.
The villagers who lost their trades were ones I hadn't traded with. Except for one villager where I think I traded with them once, but they were still novices (traded for a mending book).
But villagers shouldn't be resetting/losing trades at all when their jobsite blocks aren't being broken. There's a valid path from anywhere in the village to their jobsite.
Further, I just caught two villagers using the same jobsite. I broke it while they were doing so, and both immediately lost their professions. But only one claimed it when I re-placed it.
Still seeing this with 1.16.4.