Excel Macros Spreadsheets Not Loading

I've spent some time with Microsoft Support (almost 3 hours, including uninstalling my MS 365 and reinstalling it), but I'm having an issue with my Excel Macro spreadsheets not loading at all.

This is what I get each time.  

Also having an issue with non-Macro spreadsheets that I'm unable to use the Bold, Italic, and Underline functions (get the spinning wheel and then Excel Not Responding), as well as not able to use the Format function (get the same spinning wheel and then Excel Not Responding).

I've been using these same Excel Macro Spreadsheets for over 15 years.  Please help!