Hey there @Dudey38, 

Thanks for your reply and the detailed info you sent. 

Could you make sure that Spotify has all necessary permissions enabled in your mobile device?

1. Open your Settings menu.
2. Scroll to the bottom to find Spotify and open the app settings.
3. Enable everything you see.

On another note, do the notifications that cause the issue produce sound? If so, could you check if making them silent or setting the phone on vibrate/mute makes a difference?

We'll be waiting for your reply.