I just discovered something odd happening with a password policy in one of the Windows Server 2012 R2 environments we manage, and we have had no luck finding any information to explain the behavior.
The password policy has a minimum password length set to 12 characters but trying to set a password to exactly 12 characters is not accepted - you have to have 13+ characters. It doesn't matter what character it is, or if the first 12 characters meet all complexity requirements (age, mixed case, special characters, etc.) - if you don't have the minimum password length + 1 or greater it doesn't accept it. If the policy is changed to set 11 as the minimum, it will only accept 12 or more.
This is very confusing and contradictory to every other environment we manage.