How to set up Facebook Log In For Business in my Facebook App?

Question

I have created an app on Facebook that requires users to log in with their Business account, as I need to call some business-related APIs to provide service for them.

But I found that after my business account gets verified and everything gets settled, logging in with that app still send me to the page showing that "It looks like this app isn't available".

Then I tried again on private mode. This time, it gives me a different error message:

"Facebook Login is currently unavailable for this app as we are updating additional details for this app. Please try again later."

Is there something I should fix on my side in order to be able to log in in my app? The account I am using has a related business account so it should not be the issue.

PS. I tried with another app that uses client log in (not business log in), and that one works perfectly.