The two updates that will not install are: 2020-10 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10 Version 2004 for x64 (KB4578968), and 2020-10 Cumulative Update for Windows 10 Version 2004 for x64-based Systems (KB4579311). When inside Windows, the two updates appear to install just fine. When I reboot the machine, it attempts to install the updates, reboots a few more times, and then finally there's a message that they could not be installed. I've tried installing them separately, and I've tried to use the standalone installers from Microsoft. I'm no expert, but from looking at the CBS logs, it appears that when Windows tries to install the updates, there's a file missing. Hopefully this explanation helps - my apologies for not including more detail yesterday.