i have had the same problem as others trying to run indie games in Aurora with the exact same configurations and versions, but I think I've found a fix - or at least what works for me.
First off, my avatars were not greyed out and I was running the 17559 update. I tried toggling the usual setting such as fakelive etc. as discussed in this thread with no success. The XNA TU29 update was in the correct location under 584E07D2 but it did not show up in the details page (Y) of any of the Indie games. Also, for me, the indie games would not run from the stock dash or dashlaunch, i.e. they did not run anywhere.
What I did in the end, which seems to have fixed it, was I deleted the default path in dashlaunch and rebooted the machine to the stock 17559 dash. I did not reapply the 17559 update as suggested elsewhere in other solutions (my avatars were not greyed out). Once the xbox had restarted into the stock dash, I reset the default path back to "aurora.xex" in dashlaunch and started Aurora using the "Aurora Home" option from the home button. Now all the indie games worked perfectly. I did notice that when Aurora started up after the change it appeared to do a rescan or something similar, but it flashed past too quickly for me to catch it. As regards the indie games settings under details - "Settings Override" is disabled and the TU29 still does not appear anywhere in the options and so cannot be selected, but it is present on the HDD.
I hope this info helps someone, everything is still working after a few reboots so fingers crossed