this is likely hard to answer and mostly have experience processing photogrammetry in other software, but from that i would first question the flight parameters. do you have enough overlap? i have found that flying too low to the ground when there are lots of trees or other vertical projections can make the processing difficult. likely because of the distortion when you pass over the trees and you “see” a lot of the side of the tree. if you are higher then a larger percentage of the photo is looking at the tops of the trees and the software can then find more common points to stitch together. further to this, if there is lots of wind, then the movement of the trees can make it even worse because the common points are now not in common.
because the initial photos are failing it leads me down this direction. no way it will solve the ortho without using the majority of the photos. others might have more ideas about any settings in tbc that might help.