Unable to submit W-9 tax form

Airbnb uses simplified “substitute” version of an IRS Form W-9 to collect host's Taxpayer Identification Number for US tax reporting purposes. If Airbnb does not receive one from you, they may withhold up to 30% tax  from your earnings as a Host.

But Airbnb hosts complain they are not able to submit W-9 tax form. The Submit button is not highlighted, having no errors when completing Form W-9.

How to submit W-9 tax form?

Subscribers can see the solution in the full version of this post.