[BUG] Extraction of track ID 0 with the CodecID 'V_PRORES' is not supported.

[Selur]

can you make sense of this?

In one screenshot you are re-encoding and in the other you are re-muxing both seem to work.

extracting doesn't work but frameserving works? mhmok...?

Before extraction was done with mkvextract which does not support ProRes. (Mosu, the mkvtoolnix author, probably doesn't use ProRes.
(If you ask for it over at https://gitlab.com/mbunkus/mkvtoolnix/-/issues, Mosu might look into it, or say that he doesn't plan to support it.)
Decoding for the encoding is done through libav.
Extracting with ffmpeg also uses libav.

it only seems to become a problem if the prores profile/bit depth is too high.

iirc anything with an alpha channel is not supported by libav/ffmpeg.

Cu Selur

Ps.: uploaded a new dev which does force ffmpeg as demuxer for mkv(ProRes).