Monk Elemental invocation Meta not working

Invocations do not automatically trigger socketed skills once they have enough energy, they provide an active skill which is only usable once sufficient energy is built up, and triggers those spells when used.

You need to bind the invocation to your skill bar and then once you have built up the energy it will become usable, allowing you to then trigger the spells when you want them triggered.

Triggered skills still cost mana, this is normal.