Cognito User Pool Hosted UI "Login pages unavailable" Error Despite Correct Configuration

I'm experiencing a persistent "Login pages unavailable. Please contact an administrator." error with my Cognito User Pool hosted UI, despite having what appears to be a correct configuration.

Configuration Details:

• Region: us-east-1
• User Pool Domain: https://delta-kb.auth.us-east-1.amazoncognito.com
• App Client ID: 3c3t5mmu4iqv2ejgvv0598fhib
• Callback URL: https://d2oqy729bj8q3h.cloudfront.net
• OAuth Scopes: email, openid, profile
• Identity Provider: Cognito user pool directory (selected)

Current Status:

• Domain status: Active/Available
• App client status: Available
• Managed login pages configuration: Status shows "Available"
• All OAuth settings properly configured

Issue: When clicking "View login page" in the console or accessing the login URL directly, I get "Login pages unavailable. Please contact an administrator."

Troubleshooting Attempted:

1. Cleared browser cache and tried incognito mode
2. Tested direct login URLs with proper OAuth parameters
3. Verified all configuration settings multiple times
4. Waited for propagation delays (several hours)
5. Confirmed domain responds (base URL returns "Missing Authentication Token" as expected)
6. Verified identity provider is properly selected in app client settings

Observations:

• The domain itself is functional (responds to requests)
• Configuration appears identical to working setups
• Error persists across different browsers and networks
• Issue started immediately after initial setup

Has anyone encountered this specific error with properly configured Cognito hosted UI? Are there any hidden configuration requirements or service-level issues that could cause this?

Any insights would be greatly appreciated!