I'm not sure if this has been posted, so I figured I would as a warning. After you find the cracked White Phial and Before you read the note the assistant gives you via courier remove all briar hearts from your inventory, I didn't know and the one I had turned into a quest item and it doesn't give me credit for finding it so I can't complete the quest. Even finding another one doesn't work, I'm not worried about it for this playthrough, just trying to warn others that this could happen.