Tracking Status on LMS

Hi all

I'm publishing my first course to a new LMS. I've set my AICC_Lesson_Status equal to passed if test = 70% or above and to failed if below 70%.

When I'm testing on the LMS every now and again the status is recording as 'incomplete' but when I go back in and do it again it picks up from where I left off and doesn't record a new attempt.

I'm pretty sure I haven't lost connection and have replicated it lots of times.  I've also tried to search online for what it could be but I'm at a loss.

Hoping you can help shed some light.

Thanks :)