Spotify app only see 1 of 3 Google Cast/Chromecast devices

[FlyRoyFly]

In my spotify app I only see and can cast to 1 of 3 Vizio (2016 models) devices—1 soundbar, 2 Crave speakers. The soundbar is the one Spotify can see and cast to. However, Google Play Music app and the Google Home app have no trouble casting to all three, nor any trouble casting to any combination of grouping of the 3.

I've tried deleting these spearkers from the Google Home app, reinstalling Spotify, etc. Nothing seems to work. How can I see all of these (obviously functioning) speakers?