SharePoint Online External users redirected to ADFS sign-in page

[Gurdev Singh]

Some of our external users are experiencing weird behavior when trying to sign-in. Login flow is "User browse the site url --> enter their external signin address --> Choose 'Microsoft Account' as the account type --> Enter their password --> They get redirected to organizations ADFS sign-on page --> user enter their password and keep getting the wrong userid or password message.

I have checked in AAD portal and user is added as a 'Guest'. However, I can't understand why user is getting redirected to ADFS SSO page. As an external user with Microsoft account, user should authenticate with Microsoft Live ID, not with ADFS.

[#2]

Any solution? I currently have this issue too and these users can not access sites? This functionality doesn't seem to actually work?

[#3]

@ryanshane I would very much suspect you have the Auto-Accellertion Feature enabled for Guest Users, which means that Home Realm Discovery (HRD) will be skipped and Guest Users not able to Authenticate. Hope this helps, even it's an old post.

References: 
https://docs.microsoft.com/en-us/sharepoint/enable-auto-acceleration

https://docs.microsoft.com/en-us/azure/active-directory/manage-apps/configure-authentication-for-fed...