Insane Campain completed but no Achievment

Nearly lost my mind playing Gears 4 Insane Campain. To much for one person to handle. Act 4 Chapter 5 Boss fight was by far the worst. I consider my self a skilled player in gears achieving 100% completion in all gears of war except ultimate. Now after all that work, no achievment unlocked. Note, I did have to complete the Swarmak boss in co-op before i broke the game, but the achievment did not specify solo.

The campaign achievements sometimes take around 24 hours to pop. You might just have to be patient and wait for it.