I completed the campaign today and there was a minor issue.
Mission 4 is the major decision point of the campaign I believe and it sort of branches from there. I looked in the tech room mission simulator (campaign page) and missions 5-7 had a "B" after them (5B, 6B, and 7B).
However, I just completed the campaign and looked in the techroom and mission 8 was listed as 8A. Is there an explanation for this?