No NPC text when turning in quests

Reference report # 727,089,318

I killed the yeti in the act 4 Vaal interlude and when I clicked on Hilda to complete the quest, she opened a chat window but it was completely blank. She didn't speak audibly other than the standard greeting. I clicked around a little and nothing happened, so I pressed escape. She then presented me with the skill points book.

When I clicked on her again, she opened the standard options of currency exchange and buy/sell items.

Dialogue options were "The Spirit" and "The Vaal"

This happened to me yesterday as well when I started the quest chain in Interlude 1. The NPCs failed to tell me what my objectives were but the quests were assigned.