EMG & MRI are usually neg for most TOS, but good that no other issues to confuse /complicate things.

Mild cubital could be showing due to "double crush" those sx may show due to higher up issues than elbow.

I didn't have high pain, but very limited use and moderate discomfort, due to multi RSIs and neck/shoulder strains.
It still took approx 2.5 yrs to get to a stable point. (some delay due to work comp & 2003 limited Internet info back then)

It did take many sessions of good PT, posture work, chiropractic and focused self care.