I think I have experienced a similar issue with Spotify on my Bluesound Players. If you have a Spotify Family account, it appears only one account at a time can be connected to a Player. In other words, if my wife is connected to Spotify using her account, she will need to disconnect her Spotify account from all Players before I can connect and start listening to my own Spotify account. I believe this is a limitation of Spotify and how it authenticates account permissions on Connect players like Bluesound.
Check out this article on support.bluesound.com and maybe you'll get lucky and fix the issue you are experiencing.