Local files won't play on iphone 6S

[loftytri]

All local files worked previously on iphone 5s. They are standard mp4 files. Now on the 6s, the files sync and download no problem to the iphone, but do not play the musics. The timer progresses after I click play but no music plays from the phone. While "listening" to a local song I can change the source back to my computer which will play the song from the correct location, and then I switch back to the iphone and again no music.

Is there a software malfunction?  This is very frustrating. The files play without problem on apple itunes.