It sounds like you didn't open your RoI book until after you finished the campaign. If doing the scan patrol mission doesn't move it forward, then your only option is to play through it on your own or as fireteam leader, in order, to see if you can get it to catch up. Make sure you play the missions at their base level and not a harder version. Good luck.
Hey there, Are you sure you have done the Rise of Iron campaign on your Warlock entirely? Completing "The Iron Tomb" mission should grant you access to the next step.