Sys-audio with pci-passthrough issue: no codecs initialized

I’m building a sys-audio according to the guide: Audio qube
However, the sound card being passed through (snd-hda-intel) is not recognized in sys-audio:

nd_hda_intel 0000:00:06.0: azx_get_response timeout, switching to polling mode: last cmd=0x200f0000
snd_hda_intel 0000:00:06.0: No response from codec, disabling MSI: last cmd=0x200f0000
snd_hda_intel 0000:00:06.0: Codec #2 probe error; disabling it...
snd_hda_intel 0000:00:06.0: no codecs initialized

This is on a system with sys-gui-gpu with the integrated gfx passed through to sys-gui-gpu. The same happens if I pass-through the sound card to sys-gui-gpu. Only when both the GPU and sound card reside in dom0, the sound card is properly recognized.

I already tried a few kernel options but to no avail:
kernelopts(sys-audio): nopat iommu=soft swiotlb=8192 snd_hda_core.gpu_bind=0 snd_hda_codec_hdmi.enable_acomp=n
I’m hiding both pci devices from dom0, so I don’t think any dom0 modules / module options are related.

All sys domU use the fedora-40-xfce template with the packages installed as per the sys-audio and sys-gui-gpu guides.