I have no problem with 2-way communication between my AppleWatch Series 3 (os v8.5.1) and iPhone 12-mini (iOS v15.4.1).
The iPhone Settings shows the Apple Watch as a connected device.
However, on the [AppleWatch]->[Settings]->[Bluetooth]
I do not see the iPhone. For a baseline, I do see a desk-side speaker on the watch's bluetooth settings.
Perfect 2-way communication happens with the iMessage app and the Currently Playing Song app on the watch and the iPhone.
Ultimately, I was trying to install the ActiveOS platform on iOS, and somehow use that to enable GoogleMap's TimeLine feature on my Apple Watch via gps data caching when I'm away from the iPhone but always wearing the watch. Google Maps installs on the watch and in the Settings for that apps I maybe could connect to the iPhone to give this watch caching idea a try. I'm stuck because my watch cannot detect my iPhone using Bluetooth. But there is definitely communication happening for the iMessage and "Current Music" apps between the iPhone and watch. I guess it is via WiFi or NFC? I'm confused.
In any event, I'm in deep need of a wearable to perform location tracking. I'll accept any solution. Caching of gps coordinates for a few hours would be fine. A Timeline on Apple Maps would also be fantastic.
I've unpaired the watch and factory reset it. But, I just cannot get the watch to list the iPhone as a Bluetooth device. Yet, the watch and iPhone communicate for iMessage and Music.