Hopefully this is just a one-off oddity - except it’s happened twice…
I disabled Avast shields for 10 minutes to install a software update. Then later (longer than 10 minutes) noticed a warning shield on the Avast icon in the sys tray. So it appears that Avast did not turn one shield back on after 10 minutes. It was TWO shields the other time. Both times included the Secure DNS shield, the other time included Anti-spam. A computer reboot fixes the problem.
Attached is a screenshot. What it shows is 1) a window with a link “FIX IT” 2) an error message I receive when clicking “FIX IT” 3) Active Protection showing Secure DNS “OFF”; clicking the off button does nothing. Only way I found to turn the shield back on was to reboot.