How to resolve activation problem with child Apple ID for iMessage and FaceTime?

Gave my 10 year old nephew my wiped iPhone to use for iMessage and FaceTime. Set him up with an Apple ID and logged into the phone. For some reason his account cannot use FaceTime or iMessage. I tried logging in again with my account details and FaceTime and iMessage worked so it’s not the phone or the connection.

It just continues to say waiting for activation. I tried to follow different message boards advice to no avail.

[Re-Titled by Moderator]

Original Title: Child account with email only.