Problems playing Spotify on Firebox web browser

For the past month, out of the blue, I have been unable to play Spotify via my web browser. After troubleshooting with Spotify chat, it seems the issue is actually Firefox, because if I choose to play it via the app installed on my computer, it will play, but not via the web browser. It was display "Spotify can't play this right now".. then it will skip through three songs, play ads & then will play the first 10 seconds of audio of the next song & then it will cut out. Anyone else experiencing issues with Spotify via the Firebox web browser?