General breakage in GStreamer elements

PipeWire version (pipewire --version): 0.3.42
Wireplumber version: 0.4.5
GStreamer version: 1.18.5
Distribution and distribution version (PRETTY_NAME from /etc/os-release): Debian GNU/Linux bookworm/sid
Desktop Environment: GNOME
Kernel version (uname -r): 5.15.0-2-amd64

Description of Problem:

GStreamer pipewire elements do not work.

Steps to Reproduce:

Create a new node with pipewiresink:

GST_DEBUG=4 gst-launch-1.0 -v videotestsrc is-live=1 ! video/x-raw,format=YUY2,framerate=30/1 ! videoconvert ! pipewiresink mode=provide stream-properties="props,media.class=Video/Source,node.description=VirtCam"

Get its path with:

gst-device-monitor-1.0 Video/Source

Consume it with pipewiresrc:

GST_DEBUG=4 gst-launch-1.0 -v pipewiresrc path=93 ! identity silent=false ! videoconvert ! autovideosink

Actual Results:

No buffers are flowing.

Same happens with GStreamer audio elements.

Expected Results:

The virtual videotestsrc output from the first pipeline should show up in the second pipeline.