CPU and GPU usage very low

Hi there,

premiere rush only uses 4 of the 16 available threads to render a video. And even the 4 do not seem to be 100% utilized. The GPU is not used at all. Rendering takes more than ages for a rather short video. Even after waiting 10 minutes the rendering seems to be at 0% progress.

My hardware:
CPU: Ryzen 7 3800X
GPU: 2080S
RAM: 16GB

Thanks for your help.