I have quite annoying issue with my wife's vivomove HR, that is frequently loosing bluetooth connection (even when kept in range) and is not able to reconnect on it's own - the only thing that works is switching bluetooth on the phone off and on. Curious thing, on GCM watch has green dot but is not able to synchronise until bluetooth is swithced on and off.
My wife extensively uses call and message notifications and it's even more crucial feature for her than activity monitoring.
Now, some tech info: this has been tested on RedMi 5 Plus 4/64 (my wife's phone, Nougat) Mi MIX, good old LG G4. All firmwares up to date. All permissions checked. Power management excluded for Bluetooth and GCM. Bluetooth cache cleaned. Different binding method tested. No positive result.
On the other hand, my Forerunner 235 works with all mentioned phones flawlessly, never loosing connection when in range, and once I'm outof range and coming back, reconnects within 20-30 seconds.
I will be grateful for any helpful idea, because although this smartwatch is a piece of art for my wife, she is almost ready to throw it into river...