Air Elemental + Air Guard = Total Existance Failure
The Air Guard Knockdown effect doesn't work properly on Air Elementals (possibly other mobs too, not sure). Air Elementals just disappear instead of being knocked down (possibly because they don't have a knocked-down animation).
You don't get credit for the kill when this happens. So, the chest of the Air Elemental rare in the sands doesn't open, just stays locked with no rare around to kill. Bug reported and also got a GM to re-spawn the named Air Elemental to kill it properly.
Fully repeatable.
Radiant Servant Burst Targeting Bug
I didn't see the following listed in the OP, but maybe I missed it.
You can't have an enemy targeted when using the Radiant Servant Burst.