IdentityServer3 and No signin id passed in using custom provider for ADFS 3.0 - identityserver3

Question

I am having an issue trying to add in a custom provider into IdentityServer3 for ADFS 3.0 and was hoping someone could possibly point me in the right direction.
I have used the following references:
Middleware for external Authentication
Writing an Owin Authentication Middleware
OAUTH2 Authentication with ADFS 3
And I receive an error on the return page after coming from the IDP, returning the AuthenticationTicket.
Error
There is an error determining which application you are signing into. Return to the application and try again.
protected override async Task<AuthenticationTicket> AuthenticateCoreAsync()
{
//calls token and gets the values correctly
//context.Properties does contain a signinid
return new AuthenticationTicket(context.Identity, context.Properties);
}
The context.Properties does have a key/value pair for signinid.
And I do have all my claim data. Using this answer here
Here is the log:
18-09-13 07:44:59.412 -05:00 [Information] External login requested for provider: "https://idp.domain.com/adfs"
2018-09-13 07:44:59.417 -05:00 [Debug] Cache hit: 2
2018-09-13 07:44:59.419 -05:00 [Information] Triggering challenge for external identity provider
2018-09-13 07:45:25.389 -05:00 [Information] Callback invoked from external identity provider
2018-09-13 07:45:25.395 -05:00 [Information] No signin id passed
I am currently using:
https://localhost:xxxxx/identity/callback
/identity/callback
as my RedirectUri and CallbackPath, maybe these are incorrect? I have tried some others but received 404s.
I am just not sure what I am missing or what I am doing incorrectly, any help would be appreciated. I did do a search and found a few others had similar problems with WSFed or OpenID but there was no solutions that helped me.
Thank you.

Answer 1

After stepping through this issue (and ID Server code) I found the problem. I was receiving the no signin id error because the AuthenicateAsync("idsrv.external") call was failing inside IdentityServer3.
It was a result of the return url and callback path i used. Instead of calling /identity/callback directly I got this working by using /identity/signin-adfs and a callback path of /signin-adfs based on how the match in the custom providers given as examples were done.