In the Event Hub, you can hover over some of the events to see a list of the ~10 highest friends/guildmates in that category. I've noticed recently that in the "Level Leader" event, the levels I play during missions have subtracted from that total.

This specifically occurred multiple times for different missions, while I was helping a lower tier friend complete some of their missions that I had already completed.

Think somebody has their operators mixed up. :) Hopefully that's an easy one to fix!