The scans have an issue since the release of v17 which is yet to be solved.
The resolve button does REMOVE the threats but the animation afterwards doesn’t work for the folder scan (to show the threats have been removed).
So it does look like clicking resolve does nothing but it does remove the files.
This is a known bug to the Avast team.
Here is a video of the issue:
https://youtu.be/PDl8tb1CQC4
Only the smart scan is NOT affected by this issue.