Smart scan doesn't run

I’m running Avast One - 22.7.6025 (build 22.7.7403.741) on a windows 10 machine. When newly downloaded, smart scan runs smoothly. Thereafter, however, kicking off smart scan just results in a spinning circle which never loads and never runs.

If I repair Avast One through the windows program uninstall facility, smart scan will run - once. Then back to the spinning wheel.

Is there a fix for this?
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