New iTunes purchases don't match "On this computer" criteria after downloading

I have a Smart Playlist which include a match against 'Location' is 'On this computer'. When I download new purchases from the iTunes store, even though the download finishes and 'Show in Finder' reveals the files in their appropriate iTunes subfolders, they don't show up in my Smart Playlist. I tried quitting and restarting iTunes and it made no difference.

If I change that one criteria from 'is' to 'is not' 'On this computer' then they show up.

If I wait some amount of time (haven't determined exactly how long, but it's more than a few minutes) then they show up.

Is there a reason they wouldn't immediately show as being 'On this computer' after download is complete?