Well that is certainly a failure, as according to a very senior avast team member it should still alert.
I have just tested it I moved eicar.com test file from an excluded folder to another area and it was allowed. Not only that I was able to execute the eicar.com file as the notepad windows opened and was then closed.
But at no time did I get an avast alert whilst in silent mode. Whilst there was no alert, the eicar.com file was sent to the chest.
EDIT: change of attachment.