After tons of tentative, several workarounds and after bought a new 735 xt instead of my 235 for find a solution to the well know problem about the missing smart notifications (and fake syncronizations) issue i discovered that:
1) The problem doesn't depend by the watch
2) The problem doesn't depend by the mobile (LG G2, LG G4, S7 Edge)
3) The problem doesn't depend by Android version (Lollipop, Marshmallow, Nougat)
3) The problem doesn't depend by the BT stack
4) The problem it's partially fixed with the app GCM Runner (if somebody created an app means that the problem exist and it's enought huge)
The FIXING (in my case) is put the mobile with the GPS (of mobile ?!?!?!) in full mode (GPS + Wi-Fi + Mobile networks). From 3 days i haven't no more problems except for the mobile battery consumption.
This is quite unacceptable, any possibility to fix this problem?