Sorry, but this is a "me too" entry.
Did you get a resolution?
I have spent two days on this without success.
I know it is a fragility in Xcode, since it happened to me a week ago and resolved itself without any conscious effort on my part.
This time it's totally stuck!
I have tried rebooting all devices, re-pairing the watch, cleaning the product, removing xcuserdata, examining the watchKit app's .plist.
Xcode runs the phone component of my app fine.
It installs the app on the watch, which runs fine, but I get no debugging ourput in Xcode - which is what I desperately need to debug the app!
iMac 27-inch Late 2013
iPhone 6 iOS 11.2.1
Apple Watch 2 watchOS 4.2
Terribly frustrating !
Is there anything new besides rebooting, repairing, rerunning ?
Thank you very much !
Same issues here... Apple are you listening?
I tried running the app on the iphone only, set the scheme and destination accordingly. It seemed to work.
Any updates about this issue ?
It appears to be a weakness in connectivity between Xcode and the watch.
Recent experience suggests rebooting the watch fixes it.
After a series of resets and Control-Alt-Deletes, started working when I removed my everyday watch and put the dev watch on my wrist. I've always been able to develop with the watch on the charger before. But it it may have had more to do with the phase of the moon than anything I did.
I faced same problem.
Solution(worked for me):
1. Disconnect iOS device and uninstall the already installed app from it.
2. Restart Xcode.
3. Clean the project and erase derived data.
4. Connect iOS device.
5. Build and Run.
I hope it works for you as well.