Help with terrible training problem

Ok so first some background, I have an OTTB who is 10 yrs old. He is a great mover and great horse. However, I have just started his undersaddle training and he has had several 'melt downs'. Heres what he does, he will go in a circle pick a spot in the circle and throw his hanches to whatever direction he wants to go. If you put leg on he either doesnt respond or blows up. At first we thought it was gate sour, but he does this in every circle and just picks a spot and the completely shuts down. Doesnt respond, wont move, nothing after SEVERAL attempts by my proffessional trainer on his back he still couldnt get past it. He would go fine, and then pick a spot and throw his haunches and nothing would get him going, she would have to spin him until he was ready to go. Even young two year olds get after a while it is easier to do what they are asked then to fight, he would NOT quit fighting. Also when we were done he does this head bobbing thing that we assume is from the track, however today we tied his tongue and the second it was tied he relaxed and almost fell asleep. Once it was off back to head bobbing. Could this be some neurological problem from tongue tying? Any supliments I could give? I have tried ground training and everything and not even my proffessional trainer who has 20+ years competing and training could help.

You know, I am not a trainer, so take my thoughts here with that in mind.
I am having a little trouble visualizing what you are explaining. So,he is going around a circle, let's say to the left, and then he has decided at a certain point that her wants to go right and he lets his haunches drift out to the right?
Is this a correct synopsis?

Your trainer has tried circling him in one spot when he does this. Is she circling with his chosen direction or against it?

It sounds like he would "rather fight than switch". (a very old and lame jingle form the days when cigarettes were advertised on TV) and you mentioned that he is willing to fight much longer than any horse either of you have ever met. I read in Mark Rashid's book that his mentor told him, "horses are almost always willing to fight if you bring them a fight" or something to that effect.

Maybe, just maybe, if he moves his haunches out of the circle, you just go iwth him; the direction he wants to go. You give him nothing to fight against. You just give way and let him choose the direction but you have him keep moving, regardless of where. It might end up looking like a crazy quilt of movement. Eventually, you would add a trot to this strategy. He deflects himslef off the track you have set (at a walk). Ok, if you want to go that way, we will, but we'll trot there.

I have NO idea if this would work. I am just thinking off the top of my head.

Good luck and post a video sometime if possible.

Sounds like you need a good crop, or a good set of rounded spurs. Something to get him going. I will say though, be prepared for a bit of bucking. This might be because he is an OTTB. He doesn't know what else to do, he just doesn't know what you are asking. He doesn't know that you don't want him to run, and, stuck in a small pen with no room, he just shuts down, and therefor stops. I would just keep working with him, or use my first mentioned method. As for yearling, as you said "they even get it after a few tries", they have never been trained to run (or trot). They think "hey, go with the flow" and are more willing. He is thinking
"Is she is asking me to run? How ? I can't run here?! I don't know what she is doing!" So I would keep at it, he will eventually get it, that he needs to just walk, not run.
Hope this helps!

A video would really help... there are so many factors that we can not see. The horse could be telling us something you are not. How long have you had him before you started his under saddle training?

Get a reliable voice cue with proper lunging, and if your horse won't listen to legs while riding, use it to back up the legs - opposed to making your legs more severe with crops/spurs.

A crop doesnt make your leg more severe, it reinforces your leg aid.

Does your horse lunge ? Or lunge well ?

I say this a thousand times - but check for back pain and check saddle fit please. If the horse gets "stuck" under saddle but is great on the longe that is what I find to be the culprit 99% of the time. If he is out in his lower back, it's possible that he's disconnecting his haunches and throwing them to the side against the circle to avoid the pain, and he would do this to either direction if he was out in the lower back as opposed to just sore on one side or the other.

Palpate his back and go from there. Imo a spur or crop won't work esp if the horse is already doing this due to some sort of pain issue (or anxiety for anticipation of pain). Don't fix the symptoms, fix the issue itself and you will have corrected from the cause. Good luck!