Well, in a round about way, I seem to have fixed this.
I was having issues with photos and video getting “specified procedure could not be found” errors. I tried a bunch of solutions from many different sites will little luck, until I found this article: https://windowsreport.com/specified-procedure-could-not-be-found/.
This, finally(!) fixed that issue using this command: DISM.exe /Online /Cleanup-image /Restorehealth as described in the article. It took a while to run, but it did fix the issue I was having.
The next day, I thought I wonder if this might fix the issue I have with Brave loading extensions. Just for kicks, I tried to add an extension. It failed. I uninstalled Brave and reinstalled it and it worked! (I’d tried uninstall/reinstall Brave several times before with no joy) I’ve added a few more extensioins and it seems to be ok now.
Now, I’m not 100% certain that this really is a solution here, but, one event did follow the other, so I’m going to go with it.
I hope this sheds some light and helps somebody else out with this problem.
Thanks for the help from all of you.