The console can’t know on its own that you want to listen to a mix instead of a channel.
So you have to select the mix you want to listen to.
From then on, it will follow your mixes – until you decide you want to listen to inputs again.
But: You have selected additive mode!
This means you can also hear several mixes at the same time.
If you now select a mix, the console cannot decide whether to add or subtract this PAFL from the mixes you want to hear.
So to get the functionality you want, you would have to forego additive mode.