Blooking McAfee (1 Viewer)

[tenex]

I seem to have got rid of it now. But not sure what I did really, except I found PC App Store had been added somehow.

A quick search shows there's adware called "PC App Store" which may be the underlying problem rather than McAfee. Google it to verify that's what you've got, and uninstall it. It may not be recognized by Defender as malware per se.