[Juramentado]

Thanks folks. Fortunately, I'm real paranoid and save my campaign at every breakpoint. I reverted back to the mission where I can pick the branch, and it seems to work. Caveat though - if I pick one branch, play it for a bit, then quit out of that mission, then reload from the branching save point, picking the other branch causes the oddity where I'm credited in Arty Overload. Quitting the game entirely to desktop, then restarting and going back, things are okay. Bizarre, but a workaround nonetheless.