bmrowe

after the update, sometimes you need a hard reset, happens to me. unplug the shield and leave it off for 30 seconds and plug it back in. it should sync back up, doing a software reboot doesn't work for some reason. you have to physically unplug it. it will come back after a couple minutes after it boots up.

Do you know where those spotify apps are pulling from?  C4 has native services, so are those C4/Spotify instances or Sonos/Spotify instances?  A dealer would have to take a look - maybe you can figure that out in Composer HE if you have that....from there you could troubleshoot a few ways.
Sonos + C4 isn't that great of a pair anymore.  Personally for ease I'd stay with the native services unless Sonos offers a service you need and C4 doesn't have that service available.

Yes.  If you have a favorited playlist, you can launch it from any navigator (phone, tablet, OSD) without having your phone.  There are also properties of the C4/Spotify driver that will do things like automatically turn on a zone when you select a song in the Spotify app, etc.
This document may be useful:  https://www.control4.com/docs/product/spotify/user-guide/english/latest/spotify-user-guide-rev-a.pdf