Japan and Europe both use the same SCART connector for RGB, but they are not completely pin compatible. It is possible that you are using a cable/device that is designed with EU SCART in mind with a Saturn that needs Japan RGB 21 connector. It has been years since I've looked at the wiring but perhaps that drives your issue.
Pioneer ELITE PRO-720HD | Pioneer PDP-5010FD | Sony XBR-55X850B | LG OLED55E6P
OPPO BDP-103 | OPPO UDP-203 | Toshiba HD-XA2
PlayStation 4 Pro | Xbox One S