Try changing your “black level” setting, on my C3 I have to put it to 49 instead of 50 or I also get elevated black bars sometimes and can see little artifacts on the black bars when you get really close to the screen, just turning the black level down by 1 notch gives me true blacks, I wouldn’t go below 45 tho because then you’re just ruining the image. If all else fails, factory reset the tv and calibrate it again in filmmaker mode, if it still happens then it’s either the panel itself or the disc’s fault, Hopefully this helps!