Play Count / Last Played inconsistencies

I have a smart playlist that simply shows all music that I've never played.

I set this up to simply show music where Plays=0.

I've noticed recently that music I know I've listened to is still in the playlist, looking at the screenshot below you can see that I listened to this album in February but the play count is still zero?

I can get around this by also filtering out music where last played is not in the last 1000 months, but that's a workaround rather than a fix!