ENG 190 assignment i apparently didnt complete?

Okay so for the module 4 freewrite exercise, i completed it via macmillan and hit submit like we were supposed to, but i recieved an F for failure to submit/complete the assignment, And now when i go back to macmillan it’s empty yet brightspace shows a checkmark. i intend on emailing my professor later today but im not exactly sure how to approach this situation… any advice?