The below method appears to be patched. You'll have to complete every episode fully.
1) Load up Episode 10, Chapter 1 (preferably on Legendary)
2) Start the game, choose a loadout, quit the game.
3) Rinse and repeat for the other 4 chapters.
This can be done for every episode and can net you all of the other Spartan Ops completion achievements, and the achievements for completing Spartan Ops on every difficulty.