File conversion works fine but not videos for some reasons

Hi Team,

Converting a file works fine, but as soon as I try with a video (ex: from mp4 to mkv) either it stays at "pending" status. or i can tell my server is converting it (cpu usage goes 100%) but no status. or it goes through but i can't download it

I'm raising the problem because the file part works perfectly.

I'm on v0.17.0. running in docker. is that a known issue?
