RBR760 with firmware v6.3.8.5_1.4.80

"Do you have back up configuration files on hand to help you get the system back in to working states after the loss of the configuration?"

I just reconfigure it from scratch, without using backup file. When I get to the stage where in can upload a backup, it's only a few clicks from being done anyway, pretty simple setup. Most of the config time is booting, connecting to internet and wait times after applying settings.

"After doing factory resets and setup from scratch, and not loading any backup configurations from file, is the problem still happening with the loss of configuration after reboots? "

Yes!