The method you describe has no randomness. You are simply playing a Focus selection.
You can introduce a random element in two ways. Either:
Hit the Shuffle icon on the Queue screen after hitting Play on the focussed Tracks as above. This will play only the Tracks in the Focus, but in random order (after the first); or
Instead of Play, select Radio in the Play menu. This will play Tracks based on the Focus including Tracks not in the Focus.
If you turn on Shuffle, remember that it will remain on for that Zone until clicked off. That has tricked me many times.
Actually, I forgot but I created a bookmark “Remaining songs” with the setting “minus played”. Is there a way to have the possibility to play all shuffle on this bookmark?
Yes. When I Focus on Tracks -Played then the top left Play button becomes Shuffle. I’m unable to upload a screenshot at the moment, but do you see the same ?
I still have issues with “randomness”. I use my bookmark -Played but I still have Dream Theater & Dragon Ball Z keep appearing, even after clicking “thumb down”.
also, I have a feeling that only 10-20% of the artists are played in the bookmark.