Have you hit your t spine at all?
If your shoulders are rolled forward your t spine is not in an optimal position which doesn’t allow your shoulders to be in an optimal position.
Load ordering correctly could be painful from deviations in position.
If you don’t have an optimal position this can impact the loading order sequence.
The pain you are experiencing is your body’s way of letting you know something is wrong.
You can perform a dip out of a muscle up because your shoulder is probably in a better position when performing the muscle up vs performing dips.