MKV is a "container" and not an encoding. The encoding is what matters and if you check most Samsung manuals it usually states that it won't show if it won't play.
Fixing this is usually done by re-encoding it to a supported encoding.
I added a video (.mkv) file to my "video library", a subfolder that Samsung Link had previously pulled video files from (when doing allshare play from my PC to my Samsung Smart TV). The file, however, does not show up in the "Videos" tab of my Samsung Link account online, and I cannot play it on my TV. Does anyone know of file size/type limitations that might have caused this? Or what else may have caused this and how I can fix it?
Thank you for any help you can give.