I think being able to reproduce the symptoms at pec minor is quite telling.

I recently had an experience where a kinesiologist could manipulate my shoulder and either tighten or relax my pec minor muscle and either eliminate or reproduce my pain. It was a slam dunk that this was the problem with my left side.

The question is, why would this be a problem for you?

For example, do you do a lot of computer work? Or repetitive motion that has your shoulders forward or slouched? Work out with weights? Any of these and other "bad" movement patterns can result in your pec minor becoming adaptively short. When it does, there's not a lot of room for the nerves to travel.

If any of this resonates, I'd explore loosening up this pec minor muscle and working hard on movement patterns and posture that lessen the burden on these anterior muscles. I would NOT consider surgery until I exhaust this investigation.

And sadly, I've seen dozens of PTs myself over the years. And not a single one can connect the dots between tightness in the scalenes or pec minor, weakness in posterior muscles, overall poor posture, and a corrective regiment that attempts to fix the above.

KY