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 reinstallation of the app. Just follow the steps here. Apple has released an update to iOS, you should probably download it. You are on iOS 11.4 and it's latest version is 11.4.1 🙂
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!
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