I have Chrome 92.x, Firefox 91.x, Edge 92.x, and IE 1909 (oh, blah) on both machines.
Strangely, everything is popping up okay now. I was very concerned after only adding two K2 articles when I couldn't test. I waited from last night until this afternoon before everything started working again. Very, very scary!!!
At the same time, I never heard any complaints from my users (not that there are many with our non-profit site).
I suppose we can close the ticket, since I can no longer recreate the issue. Kind of a good problem to have, except that I won't know what to do to fix it if it happens again.
Thanks for looking into it for me.
BBC