I know it sounds simple, but it's often overlooked. Could you try restarting your device? If that doesn't help, try a quick clean reinstall of the app. Just follow these steps.
If that didn't do the trick I'd recommend checking this article.
If you're still having trouble, could you let me know the exact version of Spotify and the exact version of the operating system you're running?
I'll see what I can suggest next!