Hi Brandon. Thanks so much for reporting this issue. This sounds like a bug - we certainly don't want the Timepage SFX to interfere in any way with music played on your phone. I've done some tests and can't reproduce this behaviour, so it would be great if we could get more detail from you e.g. screenshots of your "Sounds & Haptics" settings in iOS Settings, your Notification settings for Timepage (also in the iOS Settings app), and your Sound settings inside Timepage preferences.

Please email our support team at timepage@bonobolabs.com, and ask for me, and I'll look into it further.