Shadows Disappear when Cine Cam "Constrain Aspect Ratio" false

For some reason when I turn off “constrain aspect ratio” for my cinematic camera, all my shadows in my level turn off. I’m trying to prevent the black lines (on left and right of screen) from showing up in portrait mode on my mobile devices.

Edit Also, it happens when I set the sensor height to anything less than 36.0 mm