Photos app doesn’t pause background audio when you hit play on video?

If your iPhone isn’t pausing Spotify, YouTube, or SomaFM when you play videos in the Photos app (like it used to on older iPhones), do this:

Go to:

Settings → Accessibility → Audio & Visual → Background Sounds

Then turn OFF “Use When Media Is Playing”

But it only works once per app session. After that, it breaks again unless you force-quit and relaunch Photos. It’s a weird bug and this work-around is only partial.