Office 365 Powerpoint and Excel issues on MBA M2

Powerpoint freezes each time I try to insert a graph in a presentation. Sometimes, the freeze may time out, and then a message pops up that some graphs are incompatible with others, and I should try a new one. But this happens even on a brand new file I opened just to see if the new install eliminated the problem. If I do try a new graph, the app freezes again and I have to do a force quit. I only noticed this issue within the last week, because I haven't been using the graph function lately.

Excel freezes each time I try to open a new blank workbook using file>new. I have to do a force quit to resolve the hang.

I started having the Excel file opening issue even when I had Office 2019 on this M2. This problem started about 6 months ago (time line is admittedly blurry). I moved to Office 365 in mid-April 2024, in part because I hoped that Office 365 wouldn't have the Excel new file opening issue, but it does. I have reinstalled Office 365 twice, with no change to the issues.

I have a Macbook Air M2, running Sonoma 14.5. Are there some compatibility issues between Sonoma and Office 365?

Anybody have any suggestions?