Try adding the `-pix_fmt yuv420p10le` option (e.g. before `-vf)`.

If it doesn't help, *you obviously have an inappropriate, albeit more common FFmpeg version — only for 8-bit colors.* (Your original video uses 10-bit colors.)

FFmpeg may be built for 8-bit colors or for 10-bit colors, or — in recent time —  for both of them (but I'm not sure if it's true for Matroska encoder, too). So you need to build (or obtain by other way) version for 8-/10- or 10-bit color depth.