For MCT-DOH-LGW-MLA, I would be surprised if it was not requiring 2 awards, since QR does not list that as a valid routing from MCT-MLA nor as a valid routing for DOH-
MLA
The itinerary seems to confirm that this is the case - although it describes it as the "return"
The agent or fares department should be able to identify the breakdown of whether it is pricing as a MCT-DOH plus DOH-MLA or as a MCT-LON plus LON-MLA
Might be better just buying a separate LGW-MLA ticket - business class on BA is just economy with an empty adjacent seat, so hardly worth (imo) 20,000 miles - obviously there is the issue of no protection in the case of a missed flight