With SAML in position 1 for an account's authentication, observers are unable to add more than one user as an observee. They can use the pairing code while registering the observer account. Then when they go to Account > Settings > Observing, they see a box prompting them to enter a Username rather than a pairing code, and either input will throw an error, "An error occurred. internal_server_error".
Observers should be able to add multiple observees with SAML in position 1.
Steps to Reproduce
Prerequisites: account with SAML set to position 1, and two student accounts with at least one active course.
Act as a student, go to Account > Settings, generate a pairing code.
Go to login page, and click the option to create a observer account. Create account and add pairing code.
In the observer's account, go to Account > Settings > Observing. Notice the box with Username above.
Act as the second student, generate a pairing code.
Go back as observer, try to enter the pairing code, or the student's username, and see error.