(Concluding this thread with the resolution in case anyone else
stumbles across a similar issue)
Over the Christmas holiday I was able to troubleshoot this and
determine what happened.....
At some point in the past I had created a file that was supposed to
prevent MAC address randomization (this was done to troubleshoot a
prior connectivity problem). Apparently the update to NetworkManager
caused it to *start* doing MAC address randomization instead. I
removed the file, and the problem resolved.