Transfer Music to Apple Watch Problems

Hi,

i tried to transfer Music with my iPhone and the "Apple Watch" App to my Apple Watch Series 2 . Sometimes is does not even start sync (the watch is on the charger) and if it starts sync, it stops at 99%. After a while it will start sync again from 0%.

Did you have this problem? I have the new OS on iPhone 7 and on Apple Watch 2. Restarting and a new set-up of the watch didn't help.....