For a minute I thought that was it @Stephen
[user lookup] → Show Public Profile → Activity → Assigned
It seemed a bit odd to me since assignments aren’t “publicly” visible in our instance, but okay.
… And then on closer inspection, I saw threads in “his” list that are assigned to his team not to him. In one of the team-assigned threads he’s @-ed (in a whisper), but the other looks totally random.