The boot just kept spinning for hours on end...
Recovery Environment said it could not fix the repairs - and went back to spinning dots...
Eventually, the only successful option was a system restore via a USB - the system restore of the same restore point via the SSD failed.
However , the above information - IE the problem - occurs AFTER all this, AFTER the successful system restore.
IE DISM worked fine previously, as did sfc /scannow.
Now I'm scared to even restart the computer.
[Subsequent sfc /scannow shows:
2019-01-11 18:44:25, Warning CBS Current tick count: 800 lower than last tick count: 1063. [HRESULT = 0x8007000d - ERROR_INVALID_DATA]
2019-01-11 18:44:25, Error CSI 0000000a@2019/1/11:17:44:25.535 (F) Attempting to mark store corrupt with category [l:18 ml:19]'CorruptPayloadFile'[gle=0x80004005]
2019-01-11 18:44:25, Error CBS FC: CFCAcquirerWUClient::Download(136): Result = 0x80072EE6
2019-01-11 18:44:25, Error CBS FC: CFCAcquirerWrapper::Execute(147): Result = 0x80072EE6
2019-01-11 18:44:25, Error CBS Session: 30714324_2636989176 failed to perform store corruption detect and repair operation. [HRESULT = 0x80072ee6 - Unknown Error]