Newer AVRs can show the video signal details, like 2160p, 4:4:4, 10 bit.
Yes it makes difference, because LE and CE use different default settings.
I bet if you connect your N2 directly to the tv it will work.
You can try to limit the colour depth to 8 bit and/or subsampling to 4:2:2 in Settings/System/CoreELEC