One of the cameras is probably set up in a different home than the other cameras. You will have to remove the home of the camera having the problem then add it to the other home. Be absolutely sure you do not delete the home the subscription is tied too. If you do you will lose the subscription, but will not receive a refund and it can't be fixed without signing up for a new subscription.
I apologize for my late response and thank you for all of your patience while waiting for a reply. I definitely understand how frustrating your situation must be, and I wanted to make sure that your concern was acknowledged. Do you still need help with this issue? I know that there's been a delay in response since you posted.