Media stops playing once iphone locks

Hello! My IPhone 11 has suddenly stopped playing media when I hit the side button to lock my phone. I primarily use Spotify and the podcast app, and it happens with both of them. If I play a song, and then go to lock my phone, the media stops playing and disappears altogether within a few seconds. Ive restarted my phone twice, reset all settings, closed and reopened my apps, and it is still happening. All media stops playing once I lock my phone and it is on the Lock Screen. How do I fix this? Thanks!!