Yellow tint image when connecting Sega Saturn SCART RGB to GBS-C

[unixfan2001]

Curious. Anybody here got any experience with the GBS-C upscaler?
I recently got the McBazel model (orange shell) as well as a new Sega Saturn RGB cable (I misplaced my old one).

I originally tested the new RGB cable on one of those cheapo Chinese upscalers (a black, square little metal box that spells "HD" on top) but it had issues syncing properly there. The cable works perfectly fine when hooked up to my big screen TV directly but with the GBS-C the image is tinted (no sync issues though) yellow and there is no way to adjust the blue luma channel through the knob on top of the unit.

The cable was advertised as a full RGB cable with "all pins" by the seller (Sintech in Germany). I will be testing with other devices (a GameCube and an Atari ST) momentarily.

I can actually set the red and blue luminance through the web UI but I am not sure if that is the way or if I could ever possibly hope to get something that looks accurate (usually I get red and blue but then all the yellows are completely muted).

I already updated the firmware but to no avail.

EDIT: Just tested my Atari MegaST4 with the RGB SCART cable I bought from Sintech, as well. No complaints there, thus far. TOS is being displayed correctly at least.
Could it be that the Saturn cable has the wrong type of sync for a PAL console?