Wow, thanks for this. This is very helpful, as watching people play the game helps me identify issues with it. I saw / heard some issues with performing the finishers. It should just be B button (optional + Up, Down, Left, or Right) near an opponent that is stunned. The opponent is stunned when their stun bar (the yellow bar) reaches max and they go into a looped animation.
Though it's not out of the realm of possibility that a bug occurred! Thanks again for playing, I got a lot of info from this.