Voltaic Mark with Expanse support incorrectly applies cooldown to the nova instead

Issue: When using Voltaic Mark with the Expanse support gem, the added cooldown from Expanse does not apply to the cooldown of Voltaic Mark cast's itself but to the lightning nova explosion instead. This allows the behavior where you apply Voltaic Mark kill the target and nova explodes then proceed to Voltaic Mark another target and kill it and nothing happens since the nova is on cooldown via Expanse support gem

Expected behavior: Per the description, Expanse adds +6 to the cooldown of supported skills. Voltaic Mark is a skill that procs lightning nova on enemy death, therefore the added cooldown of expanse should go to Voltaic Mark on use.

Steps to reproduce:

1. Link Voltaic Mark with Expanse support

2. Cast Voltaic Mark on an enemy

3. Kill that enemy and proc the lightning nova explosion

4. Before 6 seconds cast Voltaic Mark on to another enemy and kill it to observe that the nova does not proc


Either this is a bug or one of the gem's description needs clarification to indicate it applies to the nova and not the skill itself.