Go to your Facebook business manager account. Under business settings, go to business info. Provide your email address and click on " Send verification Email"
Go to your inbox and verify it. If not found in primary inbox, try checking under social tab or spam. Once verified, edit your facebook campaign on shopify and re-submit it.
There are no incorrect fields - there are no errors at all in the Ads Manager. It spontaneously started working for me yesterday and I did nothing differently.
This is a Facebook issue that their devs are working on. It's intermittent and affecting only some merchants, but ongoing, and they are working on it.