Forerunner 965 running coach / Spotify conflict.

Hi….. when I am using the garmin running coach on my Forerunner 965 version 20.32 with Shokz pro headphones and listening to Spotify music on my Apple IPhone 12, after a while the voice notifications stop (mid sentence) and the music goes really quiet. This stays like this until I have finished my run. When I turn off my headphones, my phone then announces all the missing voice notifications all in one go !!!!…. This could go on for a number of seconds until finally it stops. 
I have tried turning my headphones off then back on… this cleared the fault but my run session goes back to the beginning again… which is really annoying!!! Also tried rebooting iPhone 12 and watch… but this has made no difference.

Has anybody else experienced this bug and have you found a cure????

if not will Garmin be adding this to their list of fixes next time an update is issued ???

thanks

Stu Benton 

Garmin Forerunner 965 version 20.32

IPhone 12 running on most up to date version

shokz and Spotify apps all updated