Well just (wasted another hour of my life) tested it yet again using three of my accounts as sender and as recipient, in any mix and the test works fine, but the live test fails no matter what the sender account is or what the recipient account is.
I can get the test email to send but the line test using eicar fails every time. I though that it might have something to do with the fact that I have all my shields set to Ask as the first Action, so I changed that on the Mail and File System shield to Move to Chest, nada, didn't make a blind bit of difference.
So once again after eight years and nine months of using avast this fails miserably on my system/s (and I've had a few).