what do you mean the settings on the tv ?? if i had the v6 box plugged into slot 2 it would come up and say there was no source , then if i unplugged it then replaced it into the same slot it would recognise it . but if i have it in slot 3 it recognises it .its a samsung tv about 4 weeks old.
If it's like most new Samsungs, check under settings/general/external device manager (on the TV) and note whether the HDMI settings on the TV say "HDMI UHD Color" and whether it says the same thing for HDMI 2 and HDMI 3.
Might be issues with the HDMI cable quality, but check the settings first.