Mana Tempest with Blood Magic doesnt work

As a Stormweaver, when i use Mana Tempest (spell) with Blood Magic (passive skill), the spell doesnt work and wont cast.

If i take off Blood Magic and equipe Life Tap to the Mana Tempest, the spell work propely.

The Blood Magic effect shold work like Life Tap on the Mana Tempest, correct?

It's strange that it won't cast at all, but I'd expect blood magic to not work with mana tempest, as it specifies "Mana-costing spells"

Can second this, skill doesn't work like it should.

When you take the passive, Blood Magic that eliminates mana it makes it un-castable, even with Lifetap, it just doesn't effect the skills mana cost at all.

It seems like it should convert all the mana costs to life % per second and then make this usable, but the support skill just doesn't so anything to this skill..