Hey - quick update … thought I’d share since i brought this up here and you helped.
It turns out that the issue is related to the new video player on android - on android tv (using shield) turning it off from the options allows me to play all media files again. On android phone there is no such option (or at least i can’t find one).
In any case - thanks all and sorry as this wasn’t a server side issue.
All the best 
