NDK I'm mostly lurking, but I wanted to point out a pattern I think you've never kicked (pun sort of intended). TLDR is you probably want to work on the vertical "pendulum" part of the balance and letting your arm/disc get "towed" more in that plane in better posture. This thing:
Your move has always resisted doing it reliably so it's going to take a lot of repetitive work.
~~~Don't get too hung up in the following but I couldn't help myself~~~
NDK in general, you and I still share the problem where we both tend to trap body mass/balance between the feet too much which in general I think makes many people vulnerable to weird rotations through the hips and/or tipping off the rear side and/or collapses in posture to compensate.
I don't think your balance is ever really swinging all the way back into the rear foot in the backswing like a golfer. if the yellow lines I added below are the abstract balance from the head, you are still kind of trapping the balance of your body mass between your feet. So your body's only option is to tip a bit to shift off the rear foot, and to rotate more through the hips to get the disc to swing back out rapidly rather than let your hips move in complete harmony with gravity.
"Towing" the arm/disc: Posture wise, both Simon and Sidewinder are allowing their leading elbow to swing more vertically relative to the ground
with their posture (below). I think yours has some of this dip, but you are still mostly forcing it to go rotationally around your body. That's also why in the image above Simon and Eagle can get deeper in their backswing in transition (above).
That's part of why Sidewinder had me back up with dingle arm and practice how my posture "tows" my throwing elbow back and forth more over my toes letting my throwing shoulder "dingle" more. I don't think you will be exactly the same as me on the left here, but probably something like that is going on. I think you want to work on the fundamental issue in the context of the balance issue above.
I can vouch that the dingle rebuild is making my move much more efficient and gives me more consistency when throwing, even when most of my practice has just been changes applied to my dingle drills. You can still end up throwing with plenty of horizontal form/force using the same principles if that's what you're going for. It'll probably also be easier on your body in the long run.
