I have recently updated Xcode to version 10, and now my console displays:
MyApp[1618:133310] [AXMediaCommon] Unable to look up screen scale MyApp[1618:133310
I've experienced something similar. If restarting simulator doesn't do the trick, check your UI test code. Make sure your setup calls super.setup() somewhere:
setup
super.setup()
override func setup() { super.setup() // .... }