If I close Spotify on desktop or mobile, Facebook disconnects. If I log in again, the next start I'm disconnected again. Plus when I'm connected, I can't see my friends even though they connected to Facebook. It was not a problem back then, this problem started from some months ago. And if I'm not connected to Facebook, I still can log in to Spotify whith Facebook account, so I don't understand this.
And yeah, I've got only one Facebook and Spotify account, so that should not be the problem.