ESP Ra.DE. jamma pcb now working with OSSC hdmi

[majorspawn]

Hi Guys,

I have a CBOX v2 mvs supergun, the supergun works great and is connected via OSSC + RGBs scart + to my 4k Samsung. I have been running it fine in this configuration with external atomiswave, MVS and PGM boards, no issues looks great
I have purchsed ESP Ra.DE.pcb which works great on the jamma arcade however I can't get a signal via the supergun + ossc + hdmi.
The OSSC is displaying an odd resolution when running the pcb via YCBCR or RGBs scart to OSSC (269p 15.62Hz 58.08Hz or 59.15Hz with sync enabled on jamma)
I tried the ossc with hdmi connected to a pc monitor and 2 different tvs, all say signal not supported, the board does play via supergun and standard composite yellow out ( and assuming s-video also (untested))

Questions if someone has any ideas on this:

Seems like the pcb has an odd frequency, assuming if I was to invest in another supergun or scaler I would probably have the same issue?

Is anyone using this pcb or other "cave pcbs" with a supergun and scaler? if so, what are you using and are you running the same frequencies?

any insights would be much appreciated as any steps forward would mean spending money for either a new supergun or scaler.

Thanks in advance