No audio over connection for Bose QC35ii (edit: or any headset) when in HSP/HFP profile

I'm using ArchLinux (5.10.13-arch1-2) and just switched to pipewire (0.3.21) from pulseaudio. My headset pairs and connects no problem, and the a2dp profile works a charm with the standard configuration.

I followed the connect/reconnect restart bluetooth/pipewire.socket instructions at #604 (closed) which enabled me to see the "Headset Audio (HSP/HFP)" profile in pavucontrol and select it. However, as soon as I switch to the HSP/HFP profile, I no longer hear any audio from the computer nor does my microphone send audio to the machine. In fact, trying arecord -vvv -f dat /dev/null shows only Max peak (12000 samples): 0x0000005e # 0% and seems to trigger a reconnection of the headset after a few seconds.

Strangely, on selecting the HSP/HFP profile, I do hear a change in the headset, even if nothing comes from the computer. I hear a dull white noise begin and if I brush the microphone, I can hear that inside the headset. Nothing gets to or from the computer, though.

I tried changing bluez-monitor.conf to set bluez5.headset-roles = [ hsp_hs hfp_ag ] since I get the impressoin that the QC35ii supports HFP.

Thanks for your patience and, in advance, for your help!