It is quite strange.
The display says
And its working. but the picture is terrible.
I have found if I have everything connected and turn the computer on the frequency, refresh rate and resolution is bouncing around.
However this time I turned everything on and C64 was still connected to the TV directly, with everything turned on I plugged the composite cables in to the RGB converter and the information holds steady and it displays on the LCD fine, but video capture isn’t good as it loses signal many times.
If I turn the C64 off and on the information above starts bouncing around again.
Another update, after having everything working perfectly find for about 30 mins. I turned the C64 off and on and tried the disconnecting and reconnecting the composite video cable while on trick and the OSSC is struggling to lock refresh.
It seems this setup for the C64 is very fickle. Either, the C64 refresh changes as it gets warm or the composite to RGB converter does.
I’ll just have to try and find another way of doing it.