Good evening, (I hope I'm in the right thread here)
Info:
Small problem (only for me?)
An update from
LibreELEC-RPi5.aarch64-13.0-nightly-20251208-778c292
to
LibreELEC-RPi5.aarch64-13.0-nightly-20251209-c5df4f6
[...
2025-12-08 (c5df4f6): #10771 Alsa update to 1.2.15
...]
There is no sound anymore
Only Bluetooth is selectable
I'm back on the LibreELEC-RPi5.aarch64-13.0-nightly-20251208-778c292
for now.
everything is back
Regards, jd
(translated with DeepL)
No - not only you 
It's been reported in the LibreELEC developer's Github:
[BUG] [LE13] with kernel 6.18 HDMI Audio has vanished #10775
The source of the problem looks like it has been identified in the ALSA maintainer's Git.
Now it's a question of waiting till they can generate and publish a fix so that the LibreELEC team can integrate it.
Back on LibreELEC-13.0-nightly-20251208-778c292 that works.
Its not gonna be fixed tomorrow.
We just added a fix for this issue, see https://github.com/LibreELEC/LibreELEC.tv/pull/10785, images are currently building and will be available in about 12-24h.
If you use an RPi5 please note that you need to update your bootloader before updating to current nightlies - see Important: LibreELEC 13 on RPi5 requires bootloader EEPROM 2025-02-12 or newer
so long,
Hias
Just checked Bootloader and updated to LibreELEC-RPi5.aarch64-13.0-nightly-20251213-7510e1a.img.gz and can confirm sound over HDMI, thank you 
