Not able to custom sign in to native app

I have an iOS app which uses a custom sign in page. Now, i was able to successfully login with my personal okta dev account details. But when i use my organization oktapreview account details, i get an authentication failed error. The same credentials work for browser-sign-in, but for custom-sign-in, it fails. Any Inputs on this would be really helpful.

Is the application in your organization’s preview org configured to prompt users for MFA (Application → Sign On tab)? Do you see any errors when you attempt to login?

MFA is not configured. Attaching error screenshot!
Screenshot 2021-03-18 at 11.13.34 AM|689x204

Interesting.

And this username/password combination being used works right? The user can log into Okta directly with the same credentials you are using?

Is the user you are testing with a local Okta user or are they from a Federated/Social external Identity Provider?

Yes, the same username/password even works with browser-login in the native ios app. Just custom-login fails. The user is federated okta.

huh… If you pass the same credentials to the authn endpoint, do you also encounter an error?

I get the same error.

When you said the user is federated okta, do you mean that they are a user that was created locally in Okta, or were they federated from another Identity Provider? Which is to say: does the user have a password in Okta, or do they authenticate through an external provider instead?

The user has a password in okta.

So we can better assist you, can you open a support case via the Help Center or by emailing support@okta.com?