Sadly, many Bluetooth speakers in combination with iPhones are not very good at mixed music sources (announcements and Apple music) either delaying or cutting off or muting the music or announcements. You can verify that is the issue by playing the announcements through just your iphone speaker. If they work correctly that way, then I would recommend just using a long aux cable between your phone and the speaker. You can buy an iPhone aux adapter on amazon for around $8 and a 25 ft aux cable for less than $10. Generally, the performance of the app is much better if you can avoid bluetooth.