Career mode does not recognise purchased DLC

I purchased the Game of The Year edition of DiRT Rally 2.0 on Xbox for the prior few days only to find that none of the DLC cars are showing up as available to purchase in the garage of the career mode, this is preventing the possibility of taking part in numerous daily/weekly/monthly events as well as preventing the ability to unlock some of the achievements in game.

The DLC works in other game modes both in terms of cars and stages/rallycross tracks but is not functioning in career.

To this point I have tried uninstalling and reinstalling both the DLC and the actual game but to no avail, is there any way to resolve this problem?