Thank you Lorne. I enabled Edge updates and was able to update EndPoint and RestApps and restore functionality.
The obvious followup question is: Why does the version of RestApps installed by automatic updates require an Edge update for EndPoint, and how do I get back to normal working production version?
I did not mean for my question to sound accusatory either, which I realize in retrospect it probably did. I was wondering if maybe I had made a mistake in configuration. I guess the path forward is probably to wait until the new EndPoint verison is out of Edge and update at that time?
FYI, voicemail playback seems to be broken in Edge version of RestApps. Before I received your response with better instructions I enabled Edge updates on my system and updated both EndPoint and RestApps. I was going to leave it like that, but voicemail playback did not work. I was able to delete and install normal version and am up and running but thought you may want to know.