Cinepak codec becomes v_quicktime when merging

I'm trying to remerge a .mov into an .mkv. The resulting file isn't playable by VLC. The error is

Codec not supported:
VLC could not decode the format "    " (No description for this codec)

MKVToolNix itself lists v_quicktime as the codec of the vid stream in the resulting file. I'm using the latest release (34), but it was broken before. This is all on Windows 10. I can provide (privately) a tine file as example.

Cheers.