Are you certain that is the right Group? When using a Single Mission, the majority of the whole campaign file set also loads. Also, you don't show the Properties of your Group, so is it possible you are spawning several at one time there? If you change things to be like lurker did them, you also have to limit the number of groups and the number of ships each of the groups can spawn, else you sometimes end up with Group upon Group piling together into a mess. But from what you did, you suspect the 10,500 ton tanker?
btw, the "M-KF-M" means Mast - Kingpost with Funnel right by it - Mast. I do not remember the (O)... Just another way to help identify a ship class.
