Issue with SCORM randomly stopping communicating with LMS (Moodle)

Thanks. We only recently switched to 2004 to resolve another issue. However, switched the test assessment back to 2.1 and see the same behaviour. Everything fine for 1st attempt but then sporadic recoding of results for subsequent attempts. Same whether using the 2nd attempt in the SCORM or exiting the activity and going back in. Here's log for a subsequent attempt i.e. LMS attempt 2 rather than SCORM retake (which allows 2 goes):

Notice just 2 of the 10 scores logged (at 50 & 100 i.e. questions 5 & 10). However, here's an extract of the interactions report:

These are questions 4-6, all of which are correct and should have recorded a score. I answered all 10 correctly so there should be 10 scores logged, but only 2 were, It's seeing all the interactions but not logging them all. In this case it logged the passed status hence course shows has passed. In real-world cases, there's no log of status hence remains incomplete even though the learner received a pass.

Seems to me that somewhere between receiving an interaction and recording it something is going wrong.

Anyhow, I think this confirms that the issue is in Moodle and not Storyline so will switch focus to the Moodle question raised. Here if anyone wants to follow: https://moodle.org/mod/forum/discuss.php?d=431273