It sounds like the composite video pin (which carries sync only in this case) could possibly be reversed in the male-to-male cable? In two-way cables, pin 20 goes to 19, and vice versa. The audio would also swap over. This was useful for daisy-chaining A/V equipment back in the day, but is not needed in this case.
Like this: http://pinouts.ru/VideoCables/VideoTvScart_pinout.shtml
You could probably fix that pretty easily yourself, check how the scartheads are wired in your cable.
Edit: another image https://goo.gl/images/DMCbNx
- This reply was modified 1 week, 3 days ago by Harrumph.