Exactly, stopping a scan closes the log report for it also at the point that scan was stopped. So there is no point for a resumption, had he selected Pause, then there would/should have been the ability to Resume.
Opened the avast Scan Computer section, Started a Quick Scan, closed the avastUI and the scan in progress pop-up appeared as expected, image1 (note the Resume option).
I closed this scan in progress pop-up, I opened the avastUI and low and behold the Scan was still paused with Resume button available/active.
I pressed Resume and guess what, the scan resumed, image3. I stopped the Scan and it was concluded no resume option as expected and the log had been closed for that scan with only a fraction of my normal Quick scan completed, image4.
So all in all everything working as expected.