Learners Getting Stuck Randomly in Courses

Issue:  SCORM 2004 v 3 & 4 courses getting stuck on random slides within an online course in our PeopleSoft LMS: next and submit buttons don't work.  Strangely, some learners successfully complete the course the first time through; others have to retry multiple times (and progress is NEVER saved when this issue occurs); still others never successfully get through.  

When/Where:  randomly at any time, for any learner, in any browser, in any course (Rise and Storyline) in our LMS (PeopleSoft).

Can it be replicated?  Yes.  Though the issue occurs randomly, I can replicate the exact same issue every time when I manually disconnect my network cable, then reconnect.  There's no indication that my connection dropped, but upon reconnect, the course is 'stuck'.  The only way to exit it at that point is to close the window or use the browser's back button is the only option to get out--and doing so does NOT save progress, even if progress had been saved previously.

What we've tried:  clearing cache; multiple browsers; changing player settings (launch in new window and/or using the connectivity alert).  Previous research informed us if we use SCORM 2004, our LMS requires either V3 or V4 and the Passed/Failed or Passed/Incomplete options, so we did not re-test those settings.

Testing:  one of the courses was tested in SCORMCloud and Reach 360 successfully--it never got permanently stuck in either LMS upon disconnect/reconnect.  Also tested a sample SCORM 2004 V3 course from another vendor in our PeopleSoft LMS--that course was successful, never getting permanently stuck in the course.

Question:  is there a setting I'm missing?  Do we need to alter our js files?  I'm planning to compare the published output from the sample SCORM course from the other vendor to our published output files, but there are a LOT of files to look at.  Does anyone have tips on what files to focus on?  js? xsd? xml?  Or ideas on what else to check?