I purchased my ticket using American Airlines miles and have a segment from DFW to SYD, SYD to MEL, SYD to DFW on Qantas. I am able to view and change my seat for the SYD to MEL flight on Qantas.com, but I get the below error when trying to view/change seats for the DFW/SYD segments. Does anyone know why? I tried contacting Qantas and they aren't sure. Also, I don't want to try and choose other seats with an agent. My seats have been assigned, but I would like to see what other options I have.

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