I’ve run into Windows Updates not working on a number of occasions and have usually been able to clear the issue up by stopping the Windows Update services and renaming the SoftwareDistribution folder. I recently ran into an issue where this would not work. I couldn’t install updates by manually downloading them and I couldn’t use the Windows Update Assistant to update Windows. It would look like it was working, ask for a reboot and then roll it back.
I ran a sfc /scannow and error messages pointed to corrupt packages. In the CBS.log there were complaints about missing packages.
I tried mounting the ISO I had created with the Windows Update assistant and running DISM /Online /Cleanup-Image /RestoreHealth /source:wim:F:\sources\install.wim:1 /limitaccess but this errored out as well and upon investigation there was no install.wim file on the ISO, only an install.esd.
What I found was I had to download the original Windows 10 ISO which I was able to do from this site: https://tb.rg-adguard.net/public.php
I then ran the DISM command again and it was successful. After that both the 1909 update and Windows updates worked as they should.