Quiz needs to complete of profile but we also need pass/fail grade recorded

If "the score initially goes in correctly, however 4/5 hours later the scores update," that's not a Storyline issue; that's a problem with your LMS and how it's configured to update learner progress, I think.

You may also try setting the reporting options to "Passed/Failed" or "Passed/Incomplete" and see whether that affects your LMS behavior.