This can be done on any difficulty to check your progress while in the main menu press start>Stats>Escape>RB twice to "hives" then choose individual maps, under the first stat will say "highest difficulty" if this stat is blank. you need to do that map
Alternatively if all maps show as complete check the "best time" stat to see if any time is recorded. this may only necessary if you've had problems getting Gears servers to sync save data in the past.
Credit: OneNastyGrub for pointing out the best time statistic
you must complete:
Operation 1
The Hive
The Past Hive
The Gauntlet
The Mines
The Descent
Venom Run
The Hunters
The Surge
Forever
The Wanderer
The Labyrinth
The Clock
The Trap
Last Stand
Operation 2
Ice Queen
The Link
The Detour
The Line
The Blight
The Warren
Operation 3
The Barracks
The Choke
Lethal Engagements
Melee Brawl
The Corruption
The End
Operation 4
The Malfunction
The Onslaught
The Gatekeepers
The Ambush
The Split
The Mist
Tracking progress should update once you get on the helicopter to extract.