Wow, thanks for the save guys!
I called AA and the agent put me on hold for 15 min to understand the issue. He first explained that CX wasn't able to confirm my PVG-HKG segments. When I told him that J award space was showing as available, he remarked that CX can choose not to offer those seats.
So I explained that the original awards were booked in F and CX couldn't offer F seats anymore due to an aircraft change. - If he tried to confirm PVG-HKG in J, that was fine with me. He went back, reticketed the award, and even assigned J seats.
Now my award is all-J. I don't know if he reticketed it in the original class I booked - F. He certainly didn't offer to refund the mileage difference. Is there any way to confirm this, preferably w/o calling AA?