I noticed something similar as well: After convincing Kagha to let Arabella go through persuasion and using my Sorcerer's Friends spell to get advantage, everything seemed to be fine at first and I talked to Rath next. Afterwards I noticed, that I had gotten into dialogue with Kagha again, albeit without the cinematic perspective. I *think* she was questioning me about what happened at the gate, but I don't quite remember and I was able to persuade my way out of the situation without a fight. I think I still have a save game from somewhere before that, so I can go and check again later today.
