Nintendo Pro Switch Controller - Entire controller acts as mouse (Testing in Dark Souls 3)

I can’t seem to find any one else on this forum or elsewhere with the same issue I’m having, so I thought I’d ask directly.

When I load up a game (I’m testing with Dark Souls 3), my entire Nintendo Switch Pro Controller — not the joystick — acts as a mouse input. Waving the controller around moves the mouse around. I have fiddled with Controller Settings in Steam non-stop and can’t seem to correct this behavior. In a game like Dark Souls 3 where the camera control is of paramount importance, it does render the game unplayable.

Has anyone else had this experience and found a solution?

Thanks,
Matt