Has anyone managed to eliminate lip sync issue between Samsung QN94A and Q930B?

[dkn2k]

It's taken me the best part of 2 long days to set up the above combination - which I'm now happy to say appears to be fully functional, right up to the point at which (without looking too closely), there is a very clear lack of lip sync! Now, I'd be the first one to admit I'm no expert in these matters.. but wasn't HDMI e-ARC supposed to solve this issue for me? If anyone out there has an 'oven-ready' solution...