a) are you sure you're checking routes that actually (still) have La Première?
b) your profile says you're FB Platinum - for the avoidance of doubt, you must be silver or higher in FB in order to book La Première awards

I'm now Ivory so I can't even check availability any more. I've never booked such an award - at those prices, I think it's a waste of miles.

(I would imagine all the facilities in the La Première Lounge are free of charge, although some may require a reservation. It would be a bit grubby of them to start looking for payment in there, don't you think?)