When Remuxing MKV to MP4, Subler Remuxes Audio Only, Despite Video Track Selected

[mistrrhappy]

When attempting to remux MKV to MP4, Subler is outputting only the audio in an MP4 container, not the video, despite both tracks being selected. New user, so maybe doing it wrong?

Method:
File>New>Drop MKV file into Subler window>Check boxes for both audio and video tracks>Save As>Select MP4>Choose destination>Save

Thanks for any assistance, sorry if I'm just a dummy here.

[galad87]

Hard to say without any info on the video track.

[mistrrhappy]

The video is MKV wrapper w/ VP9 codec, downloaded from a website. Is there more information that I can provide? The Subler window only displays VP9, and no other video information.

[galad87]

VP9 is not a supported format.

[mistrrhappy]

Aha! Thanks for your replies.