Xbox Series X Backwards Compability Issues

Hi all,

I've been away with work for the week and got home yesterday only to find that my Xbox One Series X had started having a new problem.

No Xbox 360 Backwards Compatible titles will launch at all. It simply shows the launch picture and at around the point you'd normally get the 360 splash animation it just dumps you back to the dashboard with no errors or other information.

Things ive tried so far include:

• Uninstalling and reinstalling the game
  
• Doing a full reset of the console (it'll be fun downloading all those games again)
  
• Offline Firmware Update of the console
  
• Using the Settings menu to clear the Xbox 360 cache
  

No avail so far. Things that might also be useful to know:

• I registered the console for the Developer mode a few weeks back. Not sure if it's related or not.
  
• I notice that if I list my entire library then it lists all games including those I own for Xbox 360 and OG Xbox, but if I use the filter menu to only show these titles then it says there aren't any in the library, which is kinda weird.
  

I've tried getting a call from Microsoft but when I get to the point where I have to specify a phone number to the Virtual Assistant I just get an error saying that they had a problem, so I don't have any means to speak to anyone direct at Microsoft.

Any ideas would be really appreciated.

:)