Having issues on a fresh install with 5.3, even with --gpu-platform 1 set as a command line option for sgminer, it's still trying to use my NVIDIA cards in an AMD/NVIDIA rig.
Can you try with --gpu-platform 2 as well? Sgminer can sometimes pick up built-in Intel devices as platform 0, and if you have both nVidia and AMD, you might have both 0, 1 and 2 as possible values.
Somehow it flip flopped and AMD is now platform 0. Not anything Awesome Miner did. It was a fresh install of Windows/drivers and for some reason sgminer is detecting it differently than in the past. I had to use platform 1 before.