WhatsApp Business phone number stuck in 'Pending' — Graph API says the number does not exist

What we are trying to do:
We are setting up a WhatsApp Business account for our SaaS platform. We have registered a phone number and are trying to finish the setup.

The problem:
The phone number +447366278919 is registered with Meta but is stuck in "Pending" status. 

When we try to use the Graph API, we get the error "Object does not exist" for the Phone Number ID. 

Additionally, the phone number does not appear at all in the asset picker inside Meta Business Manager. 

What we have checked:
We are aware that the business display name is currently under review. We are not sure if this is causing the "Pending" status or the Graph API error, but we have no other visible blockers on our end and are stuck.

What we need:
Can you please investigate why the number is stuck in "Pending", why the Graph API says the Phone Number ID does not exist, and why it is missing from the asset picker?