As a temporary measure for the full scan, since the files have already been quarantined, you could try clicking the drop down on "Auto" and choose the ignore option, just ensure Avast doesn't create an exclusion for the files in the settings.
I don't know why that's still there for you though, after a reboot, that dialog should go.
You are running the latest version of v17, right? 17.2.2288.