How do I choose which codec the proxy will use (av1_nvenc)?

I’m trying to configure Shotcut to use the av1_nvenc codec to create my proxies. I have Settings → Proxy → Use hardware encoder checked and also after clicking Configure Hardware Encoder I can see it detected 3 codecs (av1_nvenc, h264_nvenc, hevc_nvenc).

For this test I just go to a video and manually click Make Proxy from properties panel.

Even if I disable the other 2 and leave av1_nvenc checked, the resulting file is using x264 codec.

You can’t unless you change the code.

Oh, ok. I was thinking the window with the detected codecs allowed to make a selection somehow.