QAudioRecorder 'Could not create a media muxer element: ""' on Arch Linux

The same code works on Windows and Mac, so i assume an issue with the gstreamer-backend on (arch) linux.

Here is a basic example what i am trying to do:

QAudioEncoderSettings settings;
settings.setCodec("audio/vorbis");
this->recorder->setContainerFormat("ogg");
this->recorder->setEncodingSettings(settings);
this->recorder->setOutputLocation(record_url);
this->recorder->record();

(changing container and encoding to anything else (e.g. audio/PCM, wav) does not change anything)

Always the following warning can be seen and the recording does not work:

Could not create a media muxer element: ""