The app is in the App Store. The phone companion app installs on the phone just fine, but for some users it (randomly) fails to appear/install on the watch. The app does not show up in the "My Watch" listing in the iPhone Watch app either.
I saw a variety of advice sites saying this can be resolved by doing things like resetting / re-pairing the watch. Also, the app has always been approved pretty swiftly when submitting to the App Store.
So my question is: can it be something code/setup related that can be fixed at the dev level? Or is this just a pesky Apple bug?
Most users are on latest iOS/watchOS versions (11.4/4.3.1)
OK, so problem was a mismatch between OS version on the device and the target version for the watch extension in XCode. If the target version is greater then the watchOS version on Apple Watch, the app will not show up in the Watch app listing and will not install, when auto-install is on. Unfortunately, all this will happen silently, with no warning or cue in the UI.