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

I've got many notes (the yellow non-threaded formerly called comments) in my excel sheets. Since the latest software update I can not display/view my notes anymore.

The cells containing note still show the red triangle-mark, but the note does not show up when I mouse over. By clicking "show all notes" in the ribbon menu, it will just only show the connection lines between cell and invisible note rectangle. But I can not access view or even edit the notes.

Also right click on the cell -> edit note does not show anything.

is there a fix or at least a workaround existing?

regards

dewege

macos: high sierra,

excel (office 365) version 16.21.1 (190123)