Is it unusual?

I initiated a full system scan (acknowledging that it might not be as crucial as before) and returned five hours later to find it still ongoing. Opting to halt it and plan for a rerun later, I encountered an issue where, despite receiving a “scan stopped” notification, indications suggested the scan was persisting: the taskbar showed an active progress bar, and the interface continued to report an ongoing scan. However, attempting to view details only reiterated the scan had ceased, a status echoed in the scan history as an incomplete session. Despite this, the system’s CPU usage implied the scan was still active. Is it unusual for a stopped scan to seemingly continue running? Would restarting my computer be a sensible next step?

Avast version and build number [i]and[/] operating system version please.

Have you changed default scan settings?
Have you tried avast repair and restart?