Podcast not pausing during app interruptions on my iPhone SE

When listening to podcasts, the audio used to pause when interrupted - eg. I use an exercise app with occasional audio instructions, and podcasts would automatically pause and then start playing again once the app instruction had finished. Recently it has stopped doing this, and the podcast continues to play quietly in the background so I have to go back and rewind it to hear the bit I missed. Is there a way to resolve this?

[Re-Titled by Moderator]