Music not playing, any ideas all

Hi there

So i had 300 tracks on the fenix 5 plus, and i can see them, but they do not play. Weird. How would you reset music?

TBC
- i can connect the watch by usb cable to my PC, and even play the music files from there on my win10 machine, so the files are definately not corrupt
- the files were uploaded via garmin express
- i have a bluetooth headset connected, all good on that front, to the watch, but as a test i removed and readded it
- i then removed all the files, so nothing at all in the device\music folder, then readded via the express windows app 1 music file
- the file is on the device, i can see it if browse songs, but when i click it or the play all songs options it just goes to the music page and nothing happens...

yes restarted the device, no affect

its just not obvious AT ALL why the files are not playing as they music be ok as played before. Now I did change my bluetooth headset a few weeks back