This is an engine bug that affect most non-toggled transformations, excluding Chemical Rage based ones, and has been known since forever now. No, don't expect it to be fixed.
You can work around it - during the transformation period itself it is not dispellable. Click ground to move somewhere, and
while still moving:- hold down shift
- activate Elder Dragon Form (Shapeshift, etc.)
- use Manta Style
- release shift
in that order. Bam, three dragons (wolves, etc.)
