Verification Failed - Enter a valid phone number

This issue has been occurring for a while now, and everything I try including updating device firmware and resetting device just won’t resolve the problem. Not even a device update from iOS 14.8 to iOS 15 will help.

Some apps on the App Store (Not all of them) that I attempt download or update on my 12.9 2nd gen iPad Pro, I receive a alert box directing me to input my Apple ID password.

So I think, “Okay, I can simply input my password and then the app will download”. Wrong! After inputting in my Apple ID password in the box and pressing on the Download button, A second alert box shows up with the title saying “Verification Failed” and the text below stating “Enter a valid phone number”.

So I then checked to see If my phone number was mistyped on my Apple ID by going into the Settings app on my iPad. And it was typed correctly. I have constantly tried everything in the book by resetting my device, signing out of my Apple ID, checking that my Apple ID settings are correct and updating.

Any suggestions on how to resolve this issue would be greatly appreciated!

Thanks!