Sorry if it doesn’t help too much but wanted to share my experience incase it helped.
Whenever I had an issue with perma-idlers… I saved and reloaded the game and it seems to fix their queue list of work to do.
The other issue is building ‘wall’ within a building to creating partition for rooms etc, sometimes it hits the corner of the slope of the roof and causes pathing issues and then whoever gets the job never gets to work