First question should be:
What is the Project Dagger Bug?
Well, Project Dagger is the last mission of the game where you, Walker, decide to kill General Cross in order to bring an end to the authority. Sadly this bug occurs quite commonly. The bug basically happens when you have completed all of the missions for the 3 main side characters of the game (Marshall, Loosum and Kvasir) yet no new waypoint appears on your screen. In order to combat that bug you should create a manual savepoint just before the completion of the very last mission BEFORE Project Dagger gets the green light.