I was able to access the Mashonzha lounge a couple weeks ago. Check-in agent never mentioned it, but I saw the Qatar sign posted outside the lounge and asked and got admitted. Very small lounge but quiet that night. I was the only person in the lounge for most of the time I spent there! So turned out to be quite nice and much better than the over-crowded BA lounge (which I left early because it was just too busy)