Jim "the site still marks the element wrong AND the student receives a message before submitting the quiz that they haven't answered all of the questions".
That's the expected behaviour of a fill-in-the-blanks question. From a programming point of view it does not make sense to accept as correct a "not filled in" blank. Unfortunately you don't say why you need this uncommon behaviour, by providing a real-world example. If you don't want or cannot add code to your question(s) I suggest you instruct your students to answer those "correct blank blanks" by typing a zero character in them (0), or "no" or N/A or... whatever suits your situation (which we don't know of).
Looking forward to your answer.
