How to Process Change Order Process with Error

We are currently using Peoplesoft 9.2 Image 33. A change request was submitted where the price was increased for a quantity based req line that was sourced to a PO line that's marked as Amount Only. The buyer Approved the Change Request, but when she tried to Process the Change Order, the Process Status shows Error:

The Error messages and Warnings shows the following reason:

The requester is unable to update the flag on the req line to Amount Only as the req line is "Unavailable for Edit". The PO line has already been invoiced so the Amount Only flag cannot be changed on the PO either. At this point, is there anything that can be done to clear the Error?