I cannot get an Apple Watch to pair with an iPhone in the simulator even when adding a new device and pairing a watch according to these instructions. I can see from the red disconnected icon at the top of the watch that it's not paired even though Xcode thinks it is? When I tap on the Apple Watch App on the iPhone it says device not paired and to do it in Xcode.
Nothing I've tried has been able to fix including a full reinstall of Xcode. I've also tried deleting derived data as well as everything inside ~/Library/Developer/Xcode/watchOS DeviceSupport.
I also installed the Xcode 10.3 beta yesterday, could this have something to do with it?
Update: I am still not sure what caused the problem but installing Xcode Beta 10.4 fixed this issue for beta version's simulator as well as Xcode 9's simulator. 👍