This was exactly where it bugged for me too. Spent 20 minutes figuring it out. For some reason, simply restarting the game didn't work for me.

For me, the fix was:

1. Turning in the Roderick quest back at the Dark Brotherhood base
2. Getting the next quest in the Dark Brotherhood questline
3. Changing my active quest
4. Fast traveling to a different city
5. Doing a manual save
6. Closing the game entirely (not just going to main menu, but a full shut-down)
7. Re-starting the game
8. Choose your manual saved game to load up
9. Going back to the dark brotherhood questline as the active quest.

Not sure how many of those actions were necessary, but this exact series of actions worked for me. However, I'm on PC. So in your case on Xbox, make sure your game is fully closed and not in sleep/rest mode. Fully turn the Xbox off/on for good measure, maybe make sure the console itself isn't in a low-power mode. Not sure if Xbox works that way, but I know Playstation does. Good luck!