I've come across this on the idea's portal (LMS-I-4213) and from reading what this person has I put I think this could possibly be why some of learners do not register as complete and are in progress or like they've never touched a SCORM course.
This is the post...
Check (and a warning) if the user's browser has access to the CDN
We're using lots of SCORM modules in our courses, and we observer many issues with lessons not being marked as completed or people having issues accessing some of the learning content.
Investigating the issue, we have discovered that in many cases this is related to the learner's browser or firewall blocking access to some of the assets or XHR calls that are send to other domains. And in Docebo, all SCORM packages are served from a third-part domain (dcbstatic.com).
Does anyone have any ideas on what we can do or what we can advise learners so we can limit the impact for them and save on admin time?