you've got it. I think one last try on the sorting...
Being able to specify a sort in one of the searches for the ~mix opens up quite a few possibilities for us... fx...
If you say "I want a mix of 40 tracks, 20 of which will be least played '4 star' tracks, and the other 20 will be 5 star tracks I've not listened to in ages"
~Mix=40,20,{[rating]=[4] ~sort=[number plays]},20,{[rating]=[5] ~sort=[last played]}
~Mix will perform the first search, take the first twenty tracks and add them to the mix, then the same with the second search.
Then it will shuffle them and present your mix to you.
This mix will perpetually evolve as [number plays] and [last played] update in your library over time.
The ability to apply sorting in the component searches allows us some control over the the files that ~mix will add to the list, and that is as far as it goes.
If I understand you correctly, you were expecting that ~mix would process each component search in turn, giving you a single list that is a linear list of the component searches, complete with specified sorting. If I'm right, I can see why you would expect that, but unfortunately, it was never intended to work like that. The end result of ~mix has always been a shuffled list of files derived from component searches as complicated or as simple as you desire.
I'm up to my neck in Real Life™ at the moment so I've still not looked at how close you could get by sorting after the fact, though my gut is telling "not very close".
I also wondered what would happen if you made individual lists for each 'block' you want, with a final smartlist that combines them all. Again though, without testing that, I'm not sure if any kind of default sorting would kick in, which had me further thinking, could we use the ~seq function to preserve the file order as the final list is built.... bet you could