No sound when playing mkv video files

I have two ATV2’s, both jailbroken. One is doing fine, no issues. The other is used less often, but I have found several small issues, and one big one: no sound when playing any mkv video file - all other files types (avi, mp4) play fine, but whatever mkv file I select, regardless of resolution or audio codec, it is mute.

Now, as I said, this ATv2 isn’t used very often, so it hadn’t been updated in a while. I went through every relevant setting on both the ATV and Samsung TV, but to no avail. I updated Maintenance, and then installed Infuse (it was till on the Media app), but still no joy.

Does anyone have any suggestion how to resolve this?

same here … 

no f**king sound … at .mkv files -.-