excel crashing when saving csv to xlsx on mac

[NAOJKB]

I am running Microsoft Excel for Mac 2021 (macOS Catalina v 10.15.7) and suddenly, when saving a csv file to xlsx, Excel hangs up/stops working and I have to force quit in order to proceed.  The csv never saves in excel format  Help!

[#2]

@NAOJKB 

Hard to give help without a bit more info.

• So, first, can you confirm: this happens repeatedly--after the force-quite and then re-load of the csv file, it will again crash
• Second: have you been able to be successful in the past with converting csv to xlsx, with other comparable files?
• Third: could  you describe anything unusual about this particular csv file itself when compared with others you've converted in the past--size, nature of data, whatever
• Fourth: have you modified the file in any way--adding formulas, for example--before going to the "save as xlsx" step; if so, what types of formulas or functions?

And if there's anything else that might help define the situation further. OS Catalina is not the most current version of Mac OS; I don't know if updating would make a difference. 

[#3]

@mathetes thanks for your reply, here are the answers to your questions:

• yes, force quit, re-load, crash again, repeat
• yes, successful with other csv conversions, problem seems to have started randomly 
• nothing unusual, small file sizes, have converted from multiple sources many times before
• no modifications, download csv, save as xlxs - crash

I can try updating the OS, but agree it may not help.  LMK if you have any other thoughts!