I just had the same problem.
It has been fixed.
It came after I submitted an app and installed a few certificates to sign the app.
Quick Fix:
Open up KEYCHAIN ACCESS > click on MY CERTIFICATES> in there you will probably see
iPhone Developer: . You will probably see it TWICE!
Select the one with the earliest Expiration date, right click and select DELETE.
Restart Xcode if you haven’t.
Works now. 🙂