945 LTE Amazon Music - background sync?

Although I've had a handful of Garmin watches over the years, the 945 LTE is my first with Music support on board.

Recently I've been trying to use the feature a little more (1-2x per week for 30-60 minutes runs) with Amazon music specifically - I have only 2 playlists sync'd.

I almost never change the playlists on my watch and don't generally manually sync via Wi-Fi.

Twice now I have been just about to step out for a run and noted that music will not play as I need to re-sync the watch.  I presume my previous sync / token expired and it wants to be sure I still have my Amazon Music subscription (or some such).

The annoyance here is a few things:

  1. I thought the music service was supposed to background sync whenever connected to power.  Due to battery life and usage I plug in at least every week, if not even for partial charges within 3-4 days.  I assume the token lasts longer than a week, thus this background sync doesn't seem to work? (I am always nearby my wifi router when I plug in).
  2. Maybe this one is on AMZ, but it seems like merely validating my subscription is good and refreshing the valid songs on my watch should be quick (so if I only notice the issue heading out the door, I could quickly sync and still run).  Instead it seems to sync all music over again and takes an eternity to sync effectively meaning I am not using it for music this run as I am not going to wait.

Reference: Garmin Support page for Music noting it should automatically update when charging (https://support.garmin.com/en-US/?faq=mSuYzZjZ366IizCdtHCyi8)