Similar issue to Windows bug, but I also wanted to include the infinite loop I encountered on OS X 10.10.2. Person 1(Windows) makes notebook, includes note with tags, shares with Person 2 (Mac). Person 2 accesses shared notebook, all tags are added to their lists. Tags cannot be nested or deleted. Even if P1 deletes the original notebook, deletes the tag and permanently erases the notes, P2 will still have the tag visible. If I rightclick on the tag and try to delete it: “Are you sure you want to delete the tag ‘UnwantedTag’? You cannot undo this action. [Delete] —— Can’t delete ‘UnwantedTag’. This tag is in a shared notebook. Would you like to remove ‘UnwantedTag from all notes? [Remove Tag from Notes] —— Tag is now shown with zero notes, but if I try again to delete the tag I'm given the same series of messages. Syncing and restarting the program doesn't change anything or fix the error.