That is a bug. I don't know if it has changed. We do have a very old climbing anim, that looks ugly and should be deleted, that possibly someone was hoping to use back then.
You may have a big old two handed weapon in your hands that you are wanting to aim/shoot or you just plain turned your back to the ladder. In either case your hands are not on a ladder and your feet may be backwards or you broke the poor saps spine twisting it 180. Ladders + freedom are hard, which is why games like Enshrouded lock you to the wall as you climb and you can't do anything except move left/right/up/down or jump off.