Storyline 360 Quiz Scoring (multiple results slides)

I have built out a course where there are many possible quiz questions (51) but students select and only answer up to 18. This is not a question bank scenario because the students select specific topics to investigate. There is an early results slide (2.1) so that they have the opportunity to review information before answering a culminating question. Then there is a second results slide for the culminating question, and a third results slide to combine the previous results slides for LMS integration.

In my tests, the final results slide reports an accurate number of points earned but an inaccurate percentage. I checked the option to only count questions viewed, so I am unsure how else to alter this. An accurate % is really important as 1) Not all students will choose to use the full 18 questions they are allotted, and so the % calculation will vary and 2) I only see % (not raw score) reported to the LMS.

Any pointers would be greatly appreciated!