I wonder the same thing. It dissappeared after I died (i know maybe I should try and not die), but now I can't see any of that.

For anybody else that reads this, restart the scenario (from the ARMA scenario menu) and when the intro has finished you can choose to start a new game or load the old save (which load your old save ofcourse if you want to keep it). This restart will bring back your GUI with the prestige points (happened to me).