There is a different/older version of Riverside out there that is unfortunately named identically. If you have both versions installed, likely you will only see one track layout when you try to run it single player. You will actually have two directories in your GameData/Locations folder with Riverside in the name. If that's the case, I recommend deleting both and making sure you install the one linked in the Tracks & Schedule thread.

Thanks to John for reminding me, I had forgotten about this issue.