Hey,
since last Saturday I've been struggling with creating and using Sandbox Accounts to test in-app payment.
After 2 days, problem with creating new accounts has gone and since this moment, I'm not able to sign in into already created account to verify IAP.
Every time I try sign in I receive an error:
The Apple Id you entered couldn't be found or your password was incorrect"
No, matter how many accounts I create and can successfully sign in via appleid.apple.com get the same error.
I'm sign out of any account in device's Settings.
