Leon Kiriliuk, back last year ago swapped the NESRGB board to the latest one (at the time of July 30th 2019) with v2.2 firmware. It DID work before randomly when I was messing with HDMI switchers that didn’t like the OSSC before. But I moved recently and now im having issues with it again. The other funny part is my SNES is working perfectly fine though (it has de jitter too). its just my NES thats going wonky with FirebrandX profile, or when I put up 5X.
UPDATE: Okay after adjusting the H sync length to 32 and enabling HPLLx2 and upsamplerx2, My NES is running fine now at 5X 1290x1080p with optimal timing.