I put a quick map together this morning and got the same results. I was hoping that by starting a new map it would ensure i was running the most recent hangar prefab, but that doesn't seem to be the issue. I did notice that if I extract the actual factory entity from the hangar prefab, and then in it's properties, if try to look at the text edit field for what to spawn, as soon as I mouse over it I get an "invalid argument encountered" error from the editor. I can see that it says IS_Raven, but it wont even let me interact with the field to see if all mechs or the APC are listed. Something is amiss there. :/
edit... I know it's a long-shot, but if i could just get my hands on the .cry files for one official map, I think i could find the issue, or at least the area of difference.