Hi,
I’m afraid I did not understand you and what you meant to say. avast detects files and folders, marks them for deletion, then it requires a reboot to override malware file and deletes it.

But the files/folders remain hidden only, no antivirus does anything to recover/ unhidden files/folders hidden by virus.
Virus doesn't hide malware, rootkit does. Or you mean for USB based malware? Certain worms spread that way, they put himself in front of a legitimate folder and user executes them thinking he opens his legitimate folder. Is that what u meant?