Cannot add my classes on MySchedule, black screen when I do.

https://preview.redd.it/iyzibnqspszd1.png?width=990&format=png&auto=webp&s=bfed937200596ee1834b6cdd5b3c59ad9765f6b5

As the title shows. When I hit enroll and submit, it just gives me this weird black shade over it. I can't click on anything.