Yeah, I'm not sure about the antivirus but I do know, just because your antivirius is on, Windows Defender appears to be docile but it is not, it still is checking and protecting some stuff and not all of the stuff it is protecting is Windows programs and operating stuff.
I have been using my paid, not free, antivirus/malware package and been very happy with it for nearly 15 years but they merged or sold out to another company in the last year and since then they have, in my opinion, gone severely downhill and the program has gotten for more complicated and harder to make work correctly with the correct settings.
They're pushing other programs and now have their own cleanup program so a few months ago, my antivirus quit working.
I use a paid clean up program and have been very very happy with it for 7 or 8 years, but when I notified my antivirus folks that the antivirus is not working, they said the two programs, even though they've been working together for me for at least 5 years are now no longer compatible and I have to turn off my cleanup program and only run the cleanup program from the antivirus company.
Anyhow, all this said just to say that even though you turn off the antivirus to check, it doesn't actually stop it's processing unless you absolutely delete the entire program and Win10 is the same so this is a major mystery as to who is to blame.