Another thing I just noticed that is more likely the cause... You may have set it to collect overlap at 80%, but that value is only valid on the ground, not at the tops of the trees.
Your Overlap Report is not all dark blue in the area that did turn out like it would if 80% overlap had been achieved. This looks more like 70% with the light blues and greens between the passes:
Use the Ground Offset feature to collect the overlap you are trying to get up at the plane of the tops of the trees. If your trees are 30 meters high, raise that offset up 30 meters so the tops of the tress are getting 80% overlap.