I tried doing a manual update of Pro via FTP using the instructions I found in the forum.
When I did that the main page rendered correctly, but none of the other pages and posts did.
Also WordPress Admin was all text. So totally useless.
I did the whole file/database restore again and I'm back to the original problem.
The error shows missing files to be _.php. in the theme folder. Are these temporary files that Pro creates that BackWPup skips?
I appreciate your efforts to help resolve this, since as I mentioned above I need to know that Pro site can be successfully backed up and restored.
Also, I have a few backups that I've made since I began building the site. All of them are producing the same error when I restore.
BTW, I'm absolutely in love with Pro and it's versatility. That's what makes this whole situation so disappointing.