Hi Phil,
I was wrong in my assumption that you had your UI files outdated (which is the case in 90% of issues like this one). As we recently found out, there were changes in other parts of Avast that caused this issue. The team responsible for this will be issuing an uUpdate that should be released soon. I'll reply to this thread when it is out.
You don't need to do anything on your machines, the uUpdate will be applied automatically.
Dan