When did you tell the system to build it?
Have you tried to ask the system to build it again?
We have had some issues with downloading of GPX files, I had the believe it was all solved now. I can not find any tracks of a job with id 13264 in our database though.
UPDATE: I tried to build one myself. Instant ready and not possible to download. Restarted some jobs and now it seems to work again. We will definitely have to look into making that more stable.