I had a few problems falling through the map too. It was caused by a thermal launcher, which is unsurprising considering the speed at which they shoot you.
Hello, I was making my way down from one vista to another, fell into this ditch and became completely unable to get out.
I tried many times standing on the tallest point of the rock and attempting to glide onto the lowest part of the diagonal ledge, but I end up not managing to make it.
