I haven't seen this reported, but I thought it was already known, so I hope this is not a duplicate.
When finishing this quest, I got the message "Quest already closed by party, skipping reward." I was alone when I took the quest. The quest shows as incomplete in my journal.
PC: Louise Gunther
This happened to me as well, as I was leaving the QA. I was still able to close the quest and get the XP reward outside when I clicked the Quest placeable though.