The hips turn left of neutral in the reach back fine but you lack the mirroring as you throw and go into the follow through. That is robbing some pivot speed which is a big deal because all the power you generate gets multiplied the lever of the arm. So not being able to push with the left leg late in the throw because the leg is airborne before the disc has left the hand hurts too and is partially the reason for the hips not turning right. The left arm could be weightless for pivoting considerations if it moved faster forward than the rest of the body. Less mass for the legs, hips and shoulders to turn=faster pivot= more exit speed and if you can hold on to the disc long enough also more spin. Which in turn would delay the onset of fade making flights straighter and longer. Flat footedness creates injuries, robs power and and slashes consistency. Have you tried different timings and accelerations of the arm in the arm pull? As of now you start fairly early and don't have a pause in the legs and hips so the elbow never leads the throw. That robs a lot of power from the elbow chop undermining the wrist snap and disc pivot. The places where power comes from. Not because the arm is strong but because it is the conduit through which the real power sources the legs and the hips direct the energy into the disc moving fast forward.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.