My battle was Gnome, something, fully traited Drake Rider, something.
I used a Fire bomb first, and then killed them all with a Sunbird.
Drake Rider spawned a Drake in place of a Gnome (first slot obv), and when I finished the battle there is no loot.
It happened to me 3 or 4 times this weekend, but next time Ill record the whole battle.
If you have a single target troop make sure to kill the Drake Rider first!!!