I was able to get the upgrade to finally work after I uninstalled the DisplayLink driver and a Splashtop app (for using an Android device as an additional monitor) and then it finally worked. I don't know which of the two (or both) were the exact culprit, but it was driving me bonkers trying to get that update to work.
For one of my clients, HP had a drive encryption program I had to uninstall for the update to finally go. Drives had never been encrypted, HP was just running it in the background from the start.
I was able to get the upgrade to finally work after I uninstalled the DisplayLink driver and a Splashtop app (for using an Android device as an additional monitor) and then it finally worked. I don't know which of the two (or both) were the exact culprit, but it was driving me bonkers trying to get that update to work.