This is a difficult one to show as the screen shot won't show the issue so I will describe it as best as possible.

If I click preview ability for your first class and then I pick a second class that is above the first one in the list and click preview ability, I see the abilities of the first class.

This issue doesn't happen if the first chosen class is above the sevond class choice.

 

Example: pick monk and then pick cipher click preview abilities for cipher show monk abilities or monk subclass abilities

 

If I choose barabrian and then rogue I will see the correct preview abilities for the rogue.

Hey audiotremour,

 

Thanks for bringing this to our attention. There is definitely some funky stuff going on when previewing ability trees while multclassing. I've reported this issue internally and made the team aware. Thanks again for the info!