Nationwide couldn't verify identity

Hi I am doing Nationwide bank switch today, at the step of verifying identity, I have taken selfie and uploaded passport, but after a few minutes it said they couldn't verify my identity, but account is opened and said my account details will be sent to me by post.

Has anyone experienced this?

So I guess they will ask me to go to branch to verify my identity?

If account is opened, but I don't go to branch to verify my identity, what would happen? And will I still get switch offer bonus?

Thanks 🙏