Occultist's Forbidden Power doesn't grant charges when self casting Discharge

As in the thread title, when self casting Discharge costing over 200 mana, I should be spending all my power charges but getting at least 1 in return for the next cast. However, I always end up without any Power charges if I cast Discharge.

Is this a bug, or is the additional charge being added when Discharge is casting, and consumed in the process? This would be highly unintuitive, and honestly gimping this already meme-worthy build.

For the record, I'm not using Spell Echo.

Mana cost occurs almost(some fringe cases maybe idk, desync explanation below) always before the action is finished, so you will gain the power charge and immediately expend it in that discharge.

other note from my experience: I have played with flicker strike and it can cause desync with mana cost. Using Kitava's thirst: the spell in hat can trigger first and kill the mob, and flicker strike then flicker's to nothing (so on your client you may have teleported to the dead mob, but using a leap slam shows you will leap from your original pre-flicker location).