webshield site blocking module

Avast free anti-virus 18.5.2342(build 18.5.3931.0)
Windows 7 pro sp1
Avast free updated to this new version.
In the webshield/customize/site blocking:
The blocked sites that I have inputted are visible but the “enable site blocking” checkbox
will not stay checked. When I check it and click OK and leave the page the box is unchecked when I return to it and site blocking is not active. How can I get site blocking to remain active?

Refer to this thread: https://forum.avast.com/index.php?topic=220144.0

Thank you for that fast reply. I did a search before I posted but somehow missed it.