Mainbow + recurBOY issues (PAL mode)

[hellocatfood]

I have a Mainbow and I’m having trouble feeding video into it from a recurBOY when in PAL mode.

When I plug the output of the recurBOY into the video input on the Mainbow it shows the video correctly. However, when I turn up the Alpha Symmetry instead of the generated pattern all I see is a grey/white overlay. See video below

Mainbow.recurBOY.BPfSKHQWs-Y.mp4

What I should be seeing is demonstrated in the demo video 4. I have tried feeding video in from other devices and it worked fine, so I’m guessing it’s something to do with the recurBOY/Raspberry Pi?

Both the recurBOY and Mainbow are set to PAL (I’m in the UK). When both devices are set to NTSC it works.