I use Amazon music on my 965. I also have Playrun installed but mostly just use Amazon for tunes.
Since the last update, you cannot change "Music Providers" to "Control Phone" if Amazon Music is active on the device. Every time I try, it defaults back to my Amazon Playlist. Reboots etc will not fix this. The only thing that fixes it is to switch to another music provider (like Playrun) and then switch to "Control Phone." This is new behavior since the last update, I always easily switched to "Control Phone" previously. This is useful when listening to an external speaker and the phone is elsewhere and you want to skip to the next song. That's a BUG.
In addition, I got the dreaded "Playlists need to be updated for offline use" error on my run this morning. I had previously checked that the playlists would load (before I left the house) but of course once I was on the trail and I tried to load up music I got the error when it was too late to do anything about it. Is there some other way that this can be implemented? My watch has been charged within the last few days, usually it validates playlists at that time but apparently not in this case.
But the actual BUG that occurred was that the "Playlists need to be updated for offline use" message completely locked up my device, no button presses or screen taps could disable it. It was completely frozen. I had to reboot the watch and of course that meant i had to restart the activity which was already 20min in. That's a BUG.
