Hourglass Support Gem breaks Charged Staff skill

Reference: 9.168.249

If you use the support gem "Hourglass" on "Charged Staff", then the skill stops making the shock waves.

I've tried using Charged Staff, then Tempest Fury.
With the support there comes no waves, as soon as I remove Hourglass, there comes waves.
Then I can equip Hourglass again, and then there will be no waves again.

Very reproducible.

I realize now that it's the cooldown that applies to the waves.
I dont know if this is intended, i just thought it would be the skill itself.