The file is scanned because the on-access scanner window lists it as scanned. Anyway, even a reboot didn't make Avast see the eicar string in a "eicar.txt". But a "pause provider", then "resume provider" did. Now avast sees the eicar string again; I was just curious if you changed something in the extension settings...
Supose it was just a glitch on my system.
KMT