It is using the nvidia encoder
2022-06-10 11:35:49.251 - INFO -> FFMpeg.Arguments: -probesize 5M -i "\\192.168.27.65\Da convertire\House\Season 08\House - S08E07 - Dead and Buried.mp4" -y -strict -2 -map 0:v:0 -c:v:0 hevc_qsv -b:v:0 3670k -minrate 2752k -maxrate 4587k -bufsize 7339k -map 0:a:0 -c:a:0 copy -map 0:a:1 -c:a:1 copy -map 0:s:0 -c:s:0 copy -map 0:s:1 -c:s:1 copy C:\Users\Admin\AppData\Roaming\FileFlows\Temp\Runner-1aa3187f-0b9e-48fc-982e-882e6491e545\a70657da-6352-4ee9-a715-15a0ac34492c.mkv
But its failing, could be the subtitle isn't supported and causing it to fail
2022-06-10 11:35:55.983 - INFO -> Press [q] to stop, [?] for help
2022-06-10 11:35:56.004 - INFO -> [h264 @ 0000021ba36f7480] no frame!
2022-06-10 11:35:56.024 - ERRR -> Error while decoding stream #0:0: Invalid data found when processing input
2022-06-10 11:35:56.041 - INFO -> [matroska @ 0000021ba40bc7c0] Subtitle codec 94213 is not supported.
2022-06-10 11:35:56.068 - INFO -> Could not write header for output file #0 (incorrect codec parameters ?): Function not implemented