LibreELEC / Kodi crashes after 10s with 5.1 audio to RME Fireface UFX II (Class Compliant USB)

  • Hardware / OS:

    MINIX PC Intel n350 running LibreELEC 12.2.1 (Generic.x86_64)

    RME Fireface UFX II operating in Class Compliant USB Mode

    The Problem:

    Playing 2.0 audio works perfectly. Playing any 5.1 video causes Kodi to hang/crash after about 10 seconds and not play any sound. After such a hang, also gui sounds don't play anymore until reboot, which they did before the hang.

    What I've Tested:

    The RME in CC mode presents itself strictly as a 24-channel device (hw:1,0).

    speaker-test -D plughw:1,0 -c 6 -t pink via SSH works flawlessly, proving the ALSA driver and plughw can handle the 6-channel stream and pad the remaining 18 channels without crashing.

    Inside Kodi, if I select the ALSA driver, 2-channel works, but 5.1 crashes ActiveAE.

    We tried forcing asound.conf profiles (using type route to map 6 channels to the 24-channel S32_LE slave format, and type plug), and forcing Kodi to use these via guisettings.xml. It resulted in either the same 10-second crash or an infinite loading spinner.

    Disabling passthrough and locking Kodi to Fixed / 48kHz did not stop the crash.

    It seems Kodi's ActiveAE is deadlocking when trying to pass multi-channel PCM to this 24-channel Class Compliant interface, even though native ALSA handles it fine. How can I bridge this gap?

    Anyone tried to connect Libreelec with RME interfaces?

    Thank you for any advice.