So I thought my issue was relating to the difference between a Debug and a Release build as per this question: What's the difference between a "Release" Xbox 360 build and a "Debug" one? but I've since found that if I go ahead and build a Creators Club version of the game using a Debug build and deploy to the XBOX, I get the same experience I had with the Release version of my game.
However if I run the game from Visual Studio using F5 and having set the XBOX as the default platform, then the game runs as expected. If I change from Debug to Release and run with CTRL+F5 then the game also works as expected.
How would running the game with the debugger attached change the results I am getting in game? Is there any way that I can use the same approach or change the default compilation of the game so that I can use this approach to release my game?