notes attached to cells not visible, broken since last excel update (Office 365 on Mac)

I had the same problem with Office 365 on my Desktop computer.  I would hover the cross over the cell with the note, the arrow pops up pointing to the cell but no note.  I had hundreds of notes in my spreadsheet, and none would display.  I tried all the suggestions in this thread and none worked. 

Now, I also use office365 on my Laptop. The offending spreadsheet has always been stored in a dropbox folder.  I found when I opened the dropbox file with my Laptop, I could now see all my notes.   I then saved the spreadsheet to a new file in dropbox.  When I opened the new file with my Desktop, the problem was gone.  All my notes were visible.  So I closed both files, renamed the new file back the original file name, and now all the notes appear in the file with the original name.  Whether I open it with my Desktop or my Laptop.