Thank you so much for your prompt response @ccstone!
For other reasons, I restarted my iMac and things are working as expected. Also, after a fresh look, I understand the first suggestion (I hadn't yesterday). I will try the other matching options next time things fail to work.
Do you mean for me to "delete the app from my macro group and recreate it" as the first thing I try the next time it fails? Or is that the last thing to try?
I don't know what it means to delete an app from my macro group. ;-(
Also, I will update this thread as I learn more. (Apparently, Figma really does not play well with others!)