Yellow tinted picture and B knob not reacting

[markusbkk]

I recently acquired a GBS-C off of Amazon. When I first connected everything and booted up my Sega Saturn I immediately noticed the yellow tinted image. The R and the G knobs actually seem to adjust the colors, whereas the B knob doesn't seem to do anything (I can set the PB/U gain in the Web UI and that seems to somewhat adjust the blue channel. Not sure if that's the same thing though). Is my unit defective or is there something I'm missing?

The Sega Saturn is hooked up via RGB SCART and the GBS-C is set to the middle position (RGBS).