gulp this may be self-inflicted. I’m still testing now, but applying the Delta update, rebooting, then applying the Cumulative update, then rebooting, the system worked fine. Now I’m testing installing the Delta followed by the Cumulative, without a reboot in between.
Then I came across this blog post : https://technet.microsoft.com/en-us/windows-server-docs/management/windows-server-update-services/deploy/monthly-delta-update-isv-support-without-wsus?f=255&MSPPError=-2147217396
Prevent deployment of Delta and Cumulative updates in the same month
Since Delta update and Cumulative update are available at the same time, it’s important to understand what happens if you deploy both updates in the same month.
If you approve and deploy the same version of the Delta and Cumulative update, you will not only generate additional network traffic since both will be downloaded to the PC, but you may not be able to reboot your computer to Windows after restart.
If both Delta and Cumulative updates are inadvertently installed and your computer is no longer booting, you can recover with the following steps:
Boot into WinRE command prompt
(followed by instructions on removing the package via DISM, which is exactly what I had already done to recover)
It’s probably worthwhile to add logic to the Delta and Cumulative fixlets, to make each of them non-relevant if we’re in a pending restart for the other one?