Hi softwaremaniac and team.
I been having the same problem. I have tried various solution found online but none solved the problem.
The problem started with Security monthly roll-out of 2018-10 (KB4462923) and persisted with the security patches of every month since (KB4467107, KB4471318, KB4480970, KB4486563).
So, every month I tried to install the security update, fail and search for online solution until I get tired.
This time I encounter this thread and was hoping you might be able to assist me as you did for jmasc.
I am attaching SFCFix log as well FRST64 search logs for two of the failed updates (2018-10 and 2019-02).
Hope you can help solve my problem!