This is my situation as well.
Question - were you an inland applicant?
And if so who was the primary applicant? You or your wife?
In our situation, we were originally in Canada on my partner's study visa. Our child was linked to their account. I was the sponsor for PR and my partners card came a month ago and our child's card has been approved, but we haven't recieved it and mine is still processing.
SO I'm wondering if maybe when there's a change in who is the sponsor for the child, there's an extra process that happens?