It may be plug and play, it needs a driver to fonction. Always. It is essential for any connecting hardware, it's just automatic the first time you plug it. Maybe try reaching to them about it.I did try using mappings in the second column, but it didn't help, plus I like reserving the paddles for other functions when I'm sequential mode.
I just can't think of why the shifter would still register in CM, but suddenly no longer register in-game!
Sometimes my wheel doesn't start properly (T300RS), it is recognized in CM and in the driver's page, inputs are recognized, but nothing when the game run. A simple manual restart of the driver always solve the problem, has if nothing happened. Dunno why it does that tho, but it seems similar to your problem. The only thing is that the wheel do have a proper driver's page to restart it. If you don't have one for the shifter, it's surely hidden somewhere. Does it appear in your windows parameters ?
Edit : A windows restart might do something, or might not, but don't really count on it (I think it's supposed to be related to loading order, blablabla it's awfully complicate and there is no way to know it unless going deep, deep, deep in the system and breaking a few things along the way hahaha just don't)