Samsung RU7400 bought Jan 2020 was working fine connected to Sky box and Panasonic Blu-Ray DVD player through Sony STR-DN1080 receiver (to eArc HDMI) until last week. Now no picture and TV reports no signal on HDMI 3 (eArc) but sound from Sony is still good. All cables are HDMI 4K.
Taking the Sony receiver out of the set up and connecting Sky directly to TV HDMI 1, 2 or 3 does give picture (but with TV sound) and TV recognizes the HDMI source as Sky.
Connecting the Panasonic Blu-ray DVD directly to HDMI 1,2 or 3 results in 'no signal' error and TV lists HDMI source as 'unknown'. BUT connecting the DVD with same cable to an older Samsung TV HDMI 1 or 2 works fine!
Have tried TV factory reset (from TV system menu) - problem persists.
Manythansk for any suggestions!
After leaving unplugged overnight, I connected up again this morning and switched on TV.
I ignored all TV setup messages and just selected a device on the Sony receiver - Viola! Picture and sound!
Same with other device.
So - I think the problem is related to the (so-called) Smart functions following the latest automatic update.
Haven't tried Netflix yet, but it is certainly now working with all Sky channels and Blu-Ray dvds.
Having a similar issue with a Q80T 55” and a Sonos Arc via eARC. Apparently all Samsung TVs are suffering the same eARC software issue or eARC hardware burnout.