Well, after having a friend test 3 destro staves (unenchanted, fire enchantment, unenchanted with the Igneous Weapons buff) through CLS we have confirmed that the Magika recovery is completely broken.
Doing a heavy attack with a resto staff shows up in CLS as refunding Magika. No such thing occurs with Elemental Drain on the target.
At this point this either confirms that:
1) CLS is not catching whatever is used for that particular event.
2) Elemental Drain is completely broken as of patch 1.2.3