I receive event notice on my phone but no audible alert.

This is just a guess, but what you're describing sounds familiar.  I have a different brand of camera and a Samsung phone and I get the same thing - a notification pops up on my phone, but there's no audio alert.  Oddly, it triggers the alert on my smart watch (non-Samsung) and the smart watch gives me an audio alert.  I think it's something with the phone, but I haven't delved into what the problem could be.