Hi Gary,
Thanks for your latest SFCFix.zip, which I have applied (please see output SFCFix.txt). Following a restart, the SFC /scannow command has reached 74% complete, before failing again:
Microsoft Windows [Version 10.0.19043.1526]
(c) Microsoft Corporation. All rights reserved.
C:\WINDOWS\system32>sfc /scannow
Beginning system scan. This process will take some time.
Beginning verification phase of system scan.
Verification 74% complete.
Windows Resource Protection could not perform the requested operation.
Please find attached a zip of the latest CBS.log file (CBS.zip).
Thanks for your help.