Company uses office 365, I have my Thunderbird. Since a couple of weeks sync issues appear (i.e.: TB has no right to delete folders in office 365). Finding a solution took several hours in various forums - nothing helps. - the only suggestion I didn'T try so far is asking the office365 helpdesk.

Problem description: When I delete folders they reappear at the old position. empting the trash yields also reappearance in trash. Same for moving folders - a copy is made, but at the old position and empty folder remains. They are gray - so hidden folders. Overwriting obviously does not work, as the folder already exist, but is not accessible. subscribing/unsubscribing does not work. In office365 the folders do not occur. If I create a folder in office 365 (web, outlook) it appears in TB. When I delete it in office 365 (web, outlook) it disappears in office 365 (web, outlook) but reamains - in gray - in TB. By now, the number of gray empty undeleteable folders has grown significantly. Only solution I got sofar is to switch from TB to outlook. :/