The other night I attempted to update my observatory computer to ASCOM 6.4sp1 and SGP 126.96.36.199. I performed a reboot after all the updates were installed. When I started SGP, it immediately reported a problem with a missing ASCOM file and I chose the option to continue anyway. SGP then appeared and showed the setup you see when SGP is run the first time on a computer; that is, all my customization was gone.
To be honest, it was really cold and I was not in the mood to trouble shoot the problem, so I simply uninstalled both updates and returned to the previous versions of both. The previous versions worked just fine. While this could be something specific to my PC (Win10, new v1809), I just wanted to alert anyone planning this same update.
FWIW this is the original release of Win10 1809, not the updated 1809 that was released a couple of days ago.
I brought my observatory PC home with me, so I can install the updated 1809 and try this again in a more comfortable environment