When instructors attach files to announcements and select to Send Announcement Emails, and then students attempt to open the attachments, a login pop-up appears and the attachment cannot be opened.  These browser pop-ups only support authentication via default/ldap providers. If SAML is the authentication provider for Learn, attempts to login via the pop-up fails.

1. Log into Blackboard Learn as an administrator 
2. Navigate to System Admin > Courses > Create a course
3. Enroll as instructor and then enroll another user as a student with a valid e-mail address
4. Login as the instructor to create an announcement in the course
5. Attach a file in the Content Editor and select to send the announcement e-mail immediately
6. Log in as the student
7. Locate the email received and attempt to open the attachment link

Observed Behavior: 
The attachment will not open, all attempts to open it result in a pop-up which only supports default/ldap autentication providers.  Attempt to login with a SAML account will fail. 

Expected Behavior: 
The attachment opens if the user is logged in. If the user is not logged in they are directed to login over the required authentication provider - pop-up for LDAP/Default, or send to idp login page for SAML