Hello there, @c9kim Welcome to the Canvas Community. Thank you for posting your question. I'm not sure if you realized this or not, but you have posted your question in the global Canvas Community website where people from all over the world come to ask questions, suggest new feature ideas, collaborate with others, write blogs, join groups, review "how to" Guides, and a lot of other things...all about Canvas. Unfortunately, the vast majority of Community members will not be able to help answer your question directly because we only have access to our own Canvas environment...not the Canvas environment of another school such as yours. So, what I would recommend is that you reach out to your school's local Canvas administrator or your school's Online Learning (or a similar name) department ... as they should be able to help you figure out why your courses are not showing up in Canvas for you. (Also, just to be sure...are you checking your "Courses" >> "All Courses" screen?) I did a brief search on your school's website, and I came across your Canvas login page: https://canvas.ucsd.edu/. On that page, there is a link to this help site: IT Service Hub. You might try contacting someone on that page to see if they can help you out.
I hope this information will be of help to you, Chanyeong. Please let Community users know if you have any other questions about this. Good luck to you!