Browse File vs Assign Sound previewing/Preview Sound settings don't save

I’m trying to set up the s2400 to output my preview and click track to channels 7/8.
In a pads Assign Sound->F5 Preview Sound settings i have 1/2 3/4 5/6 7/8 and HP available to scroll thru and select. The only values that will stick are HP or whatever track the output of that particular pad is set to. For example if a pad is outputting to channel 3, only 3/4 or HP will hold their settings even though the other tracks are available for selection. Selecting one of the other combinations seems to work until you back out and go back to the Preview Sound settings.
I can’t tell what the intended behavior is… is it that unavailable tracks are listed or is it tracks that should be available snap to the wrong settings?

I know it is possible to preview samples through a specific set of outputs in File->Browse Files->F5 Preview Sound settings and i can also select a destination pad there.

Selecting samples from the Assign Sound page seems to be a better workflow for me so i’m wondering if these 2 ways of previewing are eventually supposed to work similarly or if i am missing something.
I see it can be a way to offer ALL and per-pad preview options, but the seemingly available channels that revert are confusing in Assign Sound.