Was Shadow Heart the last one to go in combat? There is an option of which character to select at the end of combat. I think it defaulted to the last character used in combat. I switched it to return to the character that was selected before combat started.

We should just be able to select which character to use during conversation. That would make it much more like a tabletop RPG session where the entire party can take part in conversations instead of one player while the rest just sit there and listen.