it’s not just from doing Esto Yensa 2nd - it’s happening to me after getting the cut scene trying to do it 1st
Viewing post in Pyramid Bug
But… strangest thing… just reloaded my save - picked random teams and it worked and now I can switch parties…
I also saw it switch Vahn’s sprite with the selected character when the first teammate I picked was the lead of my active party going in…
so now my best guess is that it’s something to do with state of the active party going into the location combined with how you select your team…