Also with my Amazfit BIP - the phone has a hard time connecting to the watch. Once it is connected, it stays connected quite well for many hours. But in the initial connection that takes place in the morning after my automated task "night program" (Airplane mode, DND, location off, sync off, etc) it doesn't connect easily. Sometimes I have the same problem also after several hours of not using the phone (which does not happen every day, of course!).
Usually I have to switch Bluetooth off and back on, force quit and restart the MiFit app - and even with this, it often takes an hour or so until it "suddenly" connects all by itself. I have no idea why that is, but I suspect that some background service falls asleep and doesn't easily get back on by itself.
