Halo 4 - Mission 6 - Unable to Progress Bug

I have read about this bug months ago, but didn’t think it was still in the game. Basically:

After you go up into and destroy the large unknown Covenant ship and you start moving again, the ground will be completely gone a little ways down the path. After Cortana stops talking about Rampancy and the Nemesis stops, it disappears and I die.I have tried reloading the Checkpoint and Save and Quit and then reloading from Resume and it still does it. I don’t know if there is a way to fix it apart from just reloading from Missions. But I don’t know if that will mess up Campaign Progress or not. It sucks, because this is the only real bug I have encountered in all of the Halo Campaigns in The Master Chief Collection.

Restarting the mission shouldn’t mess up campaign progress. I have never experienced the bug you mentioned, but I have had similar experiences. Once I couldn’t continue to the next mission because the post game carnage screen became unresponsive. Had to force quit the game, but the game still tracked my progress fine. Restarting the mission should fix your issue.