Thanks Jeremiah. I have seen the issue you described before and killing the PHP processes has fixed it. It did not this time. I was able to restore the database to yesterdays version and the site is back up and running. Prior to today, it has been several months since any changes were made to the site so I’m fairly confident that it has something to do with the Elementor plugin. Side note: as a rule, whenever I updated plugins, I do them one at a time and check the site for proper operation after updating each plugin for this very reason – to isolate things if something stops working. In this case, it worked after each plugin update until I updated Elementor.
I’m going to go through the steps again and will report back with my findings. Thanks again!
Rolling back to 4.7 fixed the problem but I still don’t know what the conflict is (4.9, conflict with another plugin, etc).