Glitch that happens after i change form, scrolling the stage(like in Kefka's fight)

It's a problem that happens when you call another form using the scroll stage feature, like in the final battle against Kefka: The game shows some glitchy graphics, the ATB becomes crazy and if you make act your party, their commands won't be executed immediately, they will stack and then executed all together...

here's some example:
1) Celes tries to attack, the ATB resets but nothing will happen;
2) Cyan try to use Dispatch, same result;
3) Celes casts Life2, same result;
4) Cyan casts Meteor, same result;
5) Celes casts Ultima, here's the result:
- Celes attacks;
- Celes uses Life2;
- Celes uses Ultima(all in one action );
6) Cyan's turn:
- Cyan uses Dispatch;
- Cyan uses Meteor(all in one action);

PS. If you use Quick you almost freeze the battle

I cannot figure out how to solve this glitch(i don't have enough knowledge about hacking, anyway )

So i wanted to ask to skilled hackers of this site if they were able to explain why this happens... and eventually if they know how to solve this problem.

This glitch is triggered in the video of the beta of my hack(0.9), it's not downloadable, anyway... take a look:

https://www.youtube.com/watch?v=tHu8xxdo318

Thanks anyway