Whilst I can't say for sure it would seem like the scan history data isn't complete any more.
The smart scan as far as I'm concerned is (with some exceptions) a vehicle for pushing other avast paid products.
With a resident on-access antivirus like avast, the need for frequent on-demand scans is much depreciated. For the most part the on-demand scan is going to be scanning files that would be otherwise be dormant or inert. If they were active files then the on-access file system shield would be scanning them before being created, modified, opened or executed.
I used to have avast set to do a scheduled weekly Quick scan, set at a time and day that I know the computer will be on. But I have ceased this practice for some time now, based in the above.