UPDATE:
Neither repair option corrected the issue.
I uninstalled, and then reinstalled O365. This took me back to 1807 Build 10325.20118 C2R
I verified the previous problems were not present.
Then I re-initiated Insider and executed updates, bringing me back up to 1809/10813.20004.
Sure enough, the problems re-appeared.
I'm guessing this latest release (8/17) is the culprit.