I'm having this problem in two mobile devices that are synced with a webdav server. The desktop application does not show this behavior. The item/resource, which exceeds the 100MB limit, does not exist anymore, there is no reference at all in any note/revision either to the item_id or the resource filename, yet both mobile apps are still trying to sync that item. I also searched the sqlite database in the desktop app, and there is no reference there, so the item got correctly removed from the desktop app, yet not from the mobile apps. Sadly, the "Note attachment" menu cannot be accessed from them.
Any possible solutions other than bombing both apps?