I have a copy of the APK BI app ver. 1.0.63 which is stable on current android versions 10 and 11. I just installed 2.0.69 about 4-5 days ago on a tablet and ended up removing it and downgraded. I recommend you try Smart Switch (Windows) from Samsung to create a back up of what you need...
Do you mind re-installing 5.5.5.16 and see if it still is happening? Also, who's your service with? I've been trying to get to the root of Android notifications problems which have been around for awhile. I'm not convinced it's the software . . .
Not in front of my server, . . . but go to one of your camera properties page, alerts, then send push notification configure page, then test. I think the server will tell you how many device it sent a push to. Compare that to the number of devices listed on the server and that might help...
FWIW, I'm having same issue (similar issue) with T-mobile (Android) also. Started about 6 months ago. I was looking more into the Android security, but yours being an Iphone has me scratching my head. . .
To my specific issue . . . my problem is not text or emails, its BI notifications stopped.
Here are a couple of options that work great. If you have a hub even better.
https://www.amazon.com/dp/B003IHTZEY/ref=asc_df_B003IHTZEY5995724?tag=shopz0d-20&ascsubtag=shopzilla_mp_1299-20;15682928648577727590210090301008005&creative=395261&creativeASIN=B003IHTZEY&linkCode=asn
MisterHouse...