I also experience both shadow issues on DX11 with a GTX 1080, but I figured it was some kind of optimization thing. I noticed that the game uses a very, very tiny portion of my VRAM, so I thought that maybe it's designed to use only a small amount, and it handles shadow resolution in this way to achieve that. It looks the same on my boyfriend's PC with a 1070, but I don't have any other hardware to test.