I have faithfully played and beat Halo: CE, Halo 2, Halo 3, and Halo 4 on legendary in the MCC to get the Helioskrill armor and achievement, but the level Uprising in Halo 2 will not register on this website as complete no matter how many times I beat it. Please advise?
Try completing it in one session. Without saving and coming back. This worked for me.