Odroid N2+ 4K disappeared from whitelist

[wool]

I have a Odroid N2+ running CoreElec 20.5 and directly connected to a Schneider 4K TV.
On CE 20.2 4K used to be enabled and working fine but for some time (I’m not sure since when) all 4K resolutions have disappeared from the whitelist, which now contains only 1080p/i and 720p.
I did a couple of changes to my installation in the meantime, described below. I’m not sure which one of these changes (if any) is now preventing Kodi from updating the whitelist.

• I disconnected my N2+ (running CE 20.2) from my 4K TV and connected it to a Sony 1080p TV for some time, then back to the same 4K TV. Unfortunately I forgot to set the resolution back to 4K and I did not check the whitelist after doing these changes.
• Some time later I did a fresh install of CoreElec 20.5 on an eMMC card, then using the Back-up add-on I imported a full Kodi back-up from my previous CE 20.2 install (which was on the same machine but on a µSD card).
• I did NOT change the HDMI cable or any other display settings anywhere since the time 4K was in the whitelist.

I strongly suspect the Back-up add-on is the culprit, and that doing another clean fresh install could solve the problem. But then I would need to recreate all my settings and library from scratch by hand. Is there any other way for me to force Kodi to update the whitelist?

[Portisch]

Did you try right after clean fresh install?

[wool]

No, I only saw the problem after doing the restore with the Back-up add-on.

[wool]

OK I made a clean fresh install and there is still no 4K in the whitelist after first boot.
For some reason CoreELEC can no longer detect that my TV supports 4K, even though it did with a previous version.
My only hope at this point would be that there is some way to manually edit the whitelist to add 4K.
Can somebody tell me if this is possible?

[Portisch]

@wool

Can somebody tell me if this is possible?

https://wiki.coreelec.org/coreelec:ce_support

[wool]

Installation:
Odroid N2+ running CoreELEC 20.5-Nexus on e-mmc, clean fresh install.
N2+ connected directly to Schneider LED40-SC680K (4K TV) with High-Speed with Internet HDMI cable. TV set on factory settings.

Issue:
Whitelist contains only 480p60, 720p60 and 1080p60. 4K not listed even though the TV does support it.
A previous installation with the exact same hardware and settings but with CoreELEC 19.4 on μSD had a proper whitelist with 4K listed and enabled.

Log:
https://paste.coreelec.org/YbiNIo

[Portisch]

Your TV does report no 4k.

++++++++++++++++++++++++++++++++++++++++++++++++++++
+ /sys/devices/virtual/amhdmitx/amhdmitx0/disp_cap +
++++++++++++++++++++++++++++++++++++++++++++++++++++
480p60hz*
720p60hz
1080i60hz
1080p60hz

Your EDID is empty, so no display Info from TV:
kernel: hdmitx: edid: raw data are all zeroes

[wool]

OK the problem was coming from the TV firmware not being up to date.
Sorry for bothering the CoreELEC team and thank you very much for your help.