Pretty much as the title says. If you save Shadowheart on the Nautiloid and then wake her on the beach and have her join your character, your character gets 30XP, but Shadowheart does not. Fix is to send her to camp and then have her rejoin, but shouldn't need to do that.

This happens even if you don't save her. Your fix is what I do to make sure I can level her up with the others.