Guild Wars 2

This heart in Bloodtide Coast is bugged. You cannot speak with Cesseilia to start collecting items to make potions. This only leaves killing undead in the area to complete this heart. I included a screenshot of Cesseilia’s “dialogue” when you try to speak with her.

The risen are currently attacking. Finish that event first.
Also: You can start collecting items, before you speak to her. You just have to talk to her to remove wrong ingredients or to brew a finished collection.