The interest on an I-bond is added in the fifth month after purchase — reflecting the 3 months potential penalty for early withrawal, and another month for processing.
Have you accessed your Treasury Direct account lately? Is the bond purchase listed under your “securities?”
If the bond is there, and there is still no interest posted, please respond to the email you receive telling you that your post has been answered. Give me your name, email address, and phone number in that email, and I will forward it to my contact at Treasury to see what happened.