How come when i Screen Record from on the Photos with music playing, the music stops working?

I’m trying to make a screen recorded video with music playing while on the Photos app. However, it doesn’t seem to work. I tried closing the app and playing music while recording and it works fine but as soon as i enter the photos app it just simply won’t work. I also tried restarting the device. Still wouldn’t work. iOS 12 iPhone 5s. The music app is Soundcloud.