Copying STO to return order but shipping data changed

Dear experts, we had an EHP upgrade precocious and aft the upgrade, the behaviour of this changed.

We are trying to make a instrumentality for STO, but aft copying the STO and changed the papers benignant to Return order, the information successful the Shipping tab changed, specifically the Sales Org. and Customer field, erstwhile they are expected to travel the copied STO's. Before the upgrade, we had nary contented for this. The fields are besides greyed retired truthful we are incapable to alteration it.

Due to this, we are incapable to process the consequent VL10B. Error being Shipping for income org. XXXX dist. chan. XX from works XXXX is not possible.

How tin I marque definite the information successful Shipping tab volition not alteration aft copying from STO? I person looked into the Copy controls, etc, but incapable to find the cause. Please advice!

Original STO:

After copying and alteration to Return order: