So... There are 6 keys and 6 info-fragments (looking at the icons). The 6 keys are easy: 5 missions (1),  wandering servo-skull (1), 2 bonus missions (1), 2 secret missions (1) and the final supreme mission (2). For the info-fragments, I can only find 5... 6th mission on the right path (bunker busting with khorne), secret mission on the right (Intel pursuit with khorne), 2nd mission in the middle (siege with drukhari), branch from 2nd mission on the left path (purge with rebel guard) and bottom covert mission on the left path (secure the artifact with rebel guard). 

Anyone has any idea where is the 6th info-fragment? I'm on PS4 btw.