I have had the same problem for two weeks now and I can’t find a solution. I have have found many suggestions like renaming the provisioning profile, making sure the cert and private key are in the system keychain and not the login keychain.
It worked once when a dialog popped up in the background asking if I wanted to grant access to the keychain and it magically worked. But I only saw that popup once and it has never come up again resulting in the same error you have.
Please someone give us some hope. I have spent hours looking and trying other suggestions.