Audio passthrough not working on RPi 4 since 2021.11-1 update

No – HD audio is not supported on OSMC for Raspberry Pi at this time. Some AV receivers are clever enough to deduce that an HD audio format is being bitstreamed without manual flagging – but this is rare and not properly supported.

Passthrough of non HD formats (i.e. Dolby Digital or DTS) will work as before.

Support will be possible when we move to Debian Bullseye, which has a newer version of ALSA and userspace libraries.