I'm in the final stages of this Agile class. I'm able to take the practice test unlimited amount of times. I took it once and was able to see what questions I answered wrong. I took it again, and now it says waiting for professor to grade. Why is this occurring now?
Hello, Monique Abdullah 
Canvas did experience a brief issue earlier this week with students' quiz scores not displaying, but this may or may not be relevant to your specific situation, so your instructor is in the best position to investigate and remedy this for you.
Good luck!
Hello, Monique Abdullah
Welcome to the Canvas Community! You've posted your question to a global forum where Canvas users gather to exchange their ideas and best practices about using Canvas software, and our members aren't able to answer course-specific questions such as yours. Your best course of action would be to contact the instructor directly (How do I send a message to a user in a course in the Inbox as a student?)
Canvas did experience a brief issue earlier this week with students' quiz scores not displaying, but this may or may not be relevant to your specific situation, so your instructor is in the best position to investigate and remedy this for you.
Good luck!