The objective required players to visit 4 points on the battlefield. This points are marked with waypoint (diamond) when a player is nearby and column of light. The issue is that sometime all 4 points are visited, no waypoints or columns of light are present, but objective is still at 3 out of 4. My educated guess is that the game fails to count points which are visited simultaneously by different players, i. e., one player visits points A and other player point B at the same time, both points remove markers, but are counted as 1. I never had an issue with this objective when doing it solo.