Regarding the O/P... I had actually forgotten the tornado kick, that's a reference from a LONG time ago, LOL!
I remember having problems trying to learn the damn thing, yes. There's a lot going on, and when you watch some of the Olympic level TKD people doing it, it's hard to see what it is that they're doing. I got in front of a 5th degree one time at a tournament and asked him what the heck my problem was. Guy laughed, and just told me, "Walk your way through it, then run, and then you'll be able to fly."
His attempt at being deliberately vague, and meant to make me just go train I thought.... but then I got so frustrated (probably his intent) I just did exactly what he said.
1. Walk through it -- in other words, let's say it's the right-side 360 roundhouse your're working towards. Start out left-foot forward, take a slow step forward with the right foot, turn your back to start the spinning action (still very slow, no jump) using your left hip to "pull" you around, put the left foot back down and do what is now the back leg, right side round house.
You've done a tornado kick, cool, huh. Admittedely very slowly, and without the jumping, but all the basic muscular movements are there -except for the jump.
DO the cycle of step, step, turn, reach, step and kick several times, slowly and then let yourself begin to feel how the momentum builds, in my understanding it was top-down, spine-turning torque that drives the thing.
At some point start a hopping action off of the R-foot where you'll end up itht he jump. Sooner or later you'll feel where and how hard to jump to get everything lining up and now you're running.
Then practice a gazillion times until you can fly.
Personally, I got mine to work fine on the R-side, but it was too slow for me. I'm built much better for Muay Thai, so I ended up switching down the road to leg kicks as they were meaner anyway.