That got me thinking.. and that was spot on. I have multiple SCART cables, and I was accidentally using the one which doesn’t have RGB pins wired up.. so the TV was displaying composite video, and OSSC was only getting the sync signal, no RGB video.. aargh, I feel so stupid right now 😀
So mystery solved.. after changing to proper RGB SCART cable and I can now see the actual video thru OSSC, in both X2 and X3 modes!
Thanks a lot and sorry for being stupid. Sometimes the solution is too obvious..