Barre

Hello, I am playing through the badlands and the dogs of war mission and after a while in both scenarios some or all of my unit symbols on the high command map switch from blue to black, i can still command them but it is impossible to effectively use them as i can not see there location or waypoints on the map. They just fade to black as if they where respawning. In the badlands misson the three NAPA units turn to black after awhile,usually after taking the first town, in the Dogs of War half my unit symbols dissapear, always the US troops that land, crippling the mission. Is that suppose to happen or is it a bug? I have tried searching but i did not find anything that could help me with this problem, any feedback on this annoying thing is greatly appreciated. Thanks.