No sound in flatpaks using pipewire

Help
1

Hey all,
as the title says, I get no audio output when using flatpak applications. If I install a package through nixpkgs everything works.
I wasn’t able to find a solution online, so maybe someone has an idea of why this is not working.
I have enabled pipewire and flatpak as follows:

{
services.flatpak.enable = true;
services.pipewire = {
  enable = true;
  wireplumber.enable = true;
  alsa.enable = true;
  alsa.support32Bit = true;
  pulse.enable = true;
};
security.rtkit.enable = true;
}
2

Update:
I get the following errors:

LaunchProcess: failed to execvp:
xdg-settings
[2:0920/075850.708252:ERROR:bus.cc(399)] Failed to connect to the bus: Failed to connect to socket /run/dbus/system_bus_socket: No such file or directory
[2:0920/075850.708288:ERROR:bus.cc(399)] Failed to connect to the bus: Failed to connect to socket /run/dbus/system_bus_socket: No such file or directory
[2:0920/075850.711607:ERROR:object_proxy.cc(623)] Failed to call method: org.freedesktop.DBus.Properties.Get: object_path= /org/freedesktop/portal/desktop: org.freedesktop.DBus.Error.InvalidArgs: No such interface “org.freedesktop.portal.FileChooser”
[2:0920/075850.711634:ERROR:select_file_dialog_linux_portal.cc(274)] Failed to read portal version property
[50:0920/075854.341738:ERROR:gl_surface_presentation_helper.cc(260)] GetVSyncParametersIfAvailable() failed for 1 times!
[50:0920/075903.191009:ERROR:gl_surface_presentation_helper.cc(260)] GetVSyncParametersIfAvailable() failed for 2 times!
[50:0920/075910.412197:ERROR:gl_surface_presentation_helper.cc(260)] GetVSyncParametersIfAvailable() failed for 3 times!
ALSA lib ../../pulse/pulse.c:242:(pulse_connect) PulseAudio: Unable to connect: Connection refused

[139:0920/075919.458672:ERROR:alsa_util.cc(204)] PcmOpen: default,Connection refused
ALSA lib ../../pulse/pulse.c:242:(pulse_connect) PulseAudio: Unable to connect: Connection refused

[139:0920/075919.458832:ERROR:alsa_util.cc(204)] PcmOpen: plug:default,Connection refused
[50:0920/075919.468214:ERROR:vaapi_video_decoder.cc(1206)] failed Initialize()ing the frame pool
[50:0920/075919.482058:ERROR:shared_image_factory.cc(575)] Could not find SharedImageBackingFactory with params: usage: Gles2|Raster|DisplayRead|Scanout, format: RED_8, share_between_threads: 0, gmb_type: shared_memory
[50:0920/075919.482141:ERROR:shared_image_factory.cc(575)] Could not find SharedImageBackingFactory with params: usage: Gles2|Raster|DisplayRead|Scanout, format: RG_88, share_between_threads: 0, gmb_type: shared_memory

Tho dbus is enabled as well as xdg-portals:

services.dbus = {
  enable = true;
  implementation = "broker";
};
xdg.portal.enable = true;

As I’m using the Hyprland NixOS Module xdg-desktop-portal-hyprland is also enabled.