Quiz Results not bookmarking correctly

Hi all. 

I have come across a very bizarre issue that seems to be a occurring in a couple of my recent storyline courses. The problem i'm having is that my quiz score/percentage is changing once I exit and return to the course. Let me paint the picture...

I take a quiz (10 questions), say I get 6 questions correct. My feedback screen at the end presents me with a score of 60% along with the LMS is also stating that i have scored 60%. This is fine. However, when i exit the course from the feedback screen and then re-open it, if I decide to resume the course from where I left off, for some unknown reason my percentage will have changed to 40% along with the LMS also updating itself to a score of 40%. If I exit and return once more, the percentage remains as 40%. This will not change again no matter how many times I exit the course and reopen it, unless of course I choose to retake the quiz and "reset the results". 

I have checked the suspend data and am certainly no way near to exceeding the SCORM 1.2 to character limit of 4096. I have also tried to replicate the issue on scorm cloud by publishing to SCORM 2004 and have been successful in doing so. 

I have checked all my questions to ensure they are reporting to the correct results slide and variable, alongside ensuring that each questions only adds 1 point if the user is correct. The strangest thing is that this issue has no pattern. Every time I take the quiz, I am presented with a correct percentage initially, but  is then replaced by a completely different percentage once reentering the course (for the first time only). 50% has become 44.44%, 40% has become 20%, 50% has become 70%.  There is no consistency which is making this bug very difficult to figure out. 

As i've said, this only happens on the first time you exit the course, reopen it and resume from where you left off. After that, the percentage remains as the incorrect score until I reset my results and retake the quiz. 

I am not able to upload this course to here due to the content being private. 

Any advice would be really helpful.

Thanks,

Alex