I regularly save everything on to an external Passport Ultra. Nothing goes on my computer itself. Then the Ultra is supposed to be backing up automatically to an older Passport drive. Recently, the automatic backups stopped. I manually did a total new backup of the Ultra and the older drive picked up everything from earlier, but nothing that was new on the Ultra. I can still save directly to the older drive, but it won’t automatically save changes I make to the Ultra files. The problem seems to have started when I went backwards from Windows 10 to Windows 8 because of problems with 10. I’ve check all the settings – everything seems right there… I ran the diagnostics. They say everything is working fine. Any suggestions?
It’s possible for the feature you are describing to be part of Windows 10 and not available in Windows 8.
Try a dedicated automatic backup application in order to eliminate the operating system as a factor.