Mind flay not working properly

Mana drained but no damage is made.

When Mind Flay is cast at max range the spell cancels instantly draining mana but doing no damage is done.

The spell is registered though, since the target can be afflicted by blackout (if specced into it). In addition to this, the Vanilla Mind Flay mechanics will allow the spell to remain channeled and active on a target that moves out of the original range like any other spell being cast on a moving target will allow a successful hit on targets moving 10 yards out of range, which it does not do here at the moment, instead the Mind Flay breaks instantly when the target moves out of the 20 (or 24 specced) yard range where it should not break untill 30 (or 34 specced) yard range.