In my spread sheet many of the cells show black boxes w the text

I have a spreadsheet I’ve used for over a year, no problem. Now most of the cells (when highlighted) show the text with some of the letters replaced with black boxes. these letters are not special just some of the letters. The spreadsheet when viewed as a whole does not show the black (symbols?) boxes. Can anyone help, this is really annoying and difficult to work with.

Similar issue…mine started when I migrated from a Windows 7 machine to a Windows 10.

All text and numbers shows normally in the cells themselves, but about half the letters or numbers have black boxes or rectangles over them in the edit bar. Not all cells have this issue, but most do. When I type next text into a previously unused cell, I have the same issue.

Follow-up: The issue has resolved itself. For the last 2 days, I haven’t seen any of the black boxes, even on spreadsheets that had had them. No changes to the system, no idea why this happened.