Ok so I was doin a dungeon with friends noticed I got no xo why he'll aren't we getting do from the dungeon unless we had the mission which I did and now can't get xo for dungeon again. Stupid
If your 5 levels higher then the mob, you get no exp, gold or loot (except crafting materials like leather)
This also means no Undaunted exp in private\instanced group dungeon but you can get some from the quests in there.
If you bypass all the private\instanced group dungeon until higher levels, its very hard to level Undaunted