If you've cleared your caches, power cycled your router, and reinstalled, the only other thing I can think of to try is deleting your save file. You won't lose anything as everything is server side, but refreshing it has been known to fix some weird issues.
In fact, I would do it in this order...
Make sure you have completely quit out of the game (not just dashboarded) by selecting its icon and quitting from the pop-up menu (small button to the right of the Xbox button... always forget what it's called).
Select "manage game and addons" from the same menu and delete save data by navigating to the icon in that section and using that same button This is important because there is a fast way to do it that only deletes the local save and you want it off the cloud, too, so it doesn't sync your old save again later. If you do this right you'll get a prompt asking you if you want to delete it locally or everywhere. Select everywhere. If you screw this up and delete it the other way and didn't get the option of everywhere, launch the game so it resyncs your save and do all of the above again.
Clear caches by holding down the power button on the console until it shuts down then unplugging from the wall. Leave it unplugged while you do the next steps.
Power down router and unplug power for at least 1 min.
Power router back up and let it sync to isp.
Power Xbox up, reinstall game, then test.
This is the most thorough way to make sure you've cleared absolutely everything that I know of. Good luck and let us know how it goes.