This is usually caused by the system having low confidence in your level but rather than leaving you out of the rankings, it puts you in your rightful position but grayed out. You'll notice that you don't occupy an actual position but you can see where you would be if you did.
Your level confidence can be low because you only have a small number of matches in your history, you don't have recent results or you've had some unexpected results. All these factors will reduce your level confidence and if that drops below 20% it is considered too low to include you in the listings normally.