Same problem for me UN55KU6290F all other apps Netflix. etc fine. Doesn't matter if I am playing Spotify from the app on the TV or if I am using Spotify on my phone on the the same Wifi network. It also the same problem using the TV app and if I am hardwired to the TV via Ethernet.
After research I found that this is a corrupt cash file on our TV’s. problem is we can’t access these files to delete them or relocate the file. Problem that Spotify and Samsung need to resolve. Unfortunately this might take time. 😩
Same problem on my TV Samsung UN40JU6400. I unistalled the app. Installed it again and nothing. The app keep stopping after 1 sec on the player. It's not a problem of memory space in TV. Please! Fix this version, Spotify. On the mobile, on the pc, you works fine.