I bought the Coursepress Pro grade error

I made in the unit 5 questions and check to be necessary pass all to go to next unit, and when i simulate answering it, after i answer all 5 questions, and check the results, it says i answered all 5 right, but it didn't give me 100% completion on course... as a teacher i check the student grades, and saw the last question looks that wasn't answered ... Them i came back as student, and re-answer all 5 questions.. and again the same error. they don't consider my last answer besides as student i see the question marked as answer and right answer. what should i do?