Automatic signing is unable to resolve an issue with the "projectName" target's entitlements file
I was able to resolve this by deleting all my provisional files on my computer (~/Library/MobileDevice/Provisioning Profiles) and restarting Xcode.
I was able to fix this same issue by turning on push notifications and then turning them back off.
Not sure why this works, but in Xcode 9.4.1, and Xcode 10 Beta this fix still works.
Update: This works in Xcode 10.1 & 10.2