Users who are Contacts cannot also be Blocked Users. If you want to add one of your Contacts to your Blocked Users list, you must remove this person from your Contacts list and then add this person to your Blocked Users list.

Similarly, Blocked Users cannot be Contacts. If you want to add one of your Blocked Users to your Contacts list, you must remove this person from your Blocked Users list and then add this person to your Contacts list.