I have created a Standard Campaign and then a Workflow to control what happens to users who receive the email.    We have paths for Opened and Not Opened and a path off the Opened path for Replied To, True and False.  For testing we send that Campaign to 3 different email addresses.  One of them opens it and replies, one opens it but doesn't reply and the other person doesn't open it at all.   But all  emails fed into the Workflow all end up going down the same path "Not Opened" even though the Campaign Report itself says one was Opened and Replied to.    Also the Campaign does not detect that one of the recipients Opened.   So we have two problems:  the Campaign doesn't detect one of the Opened events and the  Workflow doesn't detect ANY Opened events