Music cuts out when running


i recently bought a Venu SQ Music edition, to run and leave my phone at home. went for my first run today and as soon as i start the GPS activity the music stops - initially a lag and then just disappears. ive had my Sony WF XB700 earphones for 2 years and never had an issue with any other device. 

as soon as i stop the GPS activity the music continues 

any advise? or anyone with the same issue?