SCORM LMS Completions Storyline versus Presenter

I've had repeated problems with Presenter recording SCORM completions with one client on two different Learning Management Systems.  I have not been able to determine if the problem lies with the LMS (there are two different LMS vendors), the authoring package (Presenter).  Possibly the client's workstation or network security is blocking SCORM traffic.

The failure rate for this client recording SCORM completions has been about 8% across all employees, or about 1,500 of the 20,000 employees have taken the Presenter-authored course to completion and do not show completion on the LMS.

That's a lot of complaints.  

I have not seen this failure rate with other clients running other LMS which suggests that the problem lies outside Presenter, but try telling that to the client.  From the client's point of view, they've given Presenter two chances, over two years, on two different LMS with the same results.

All that said, and I realize the evidence doesn't point to Presenter but:  Is there anything new in Storyline's SCORM implementation that might suggest it would track SCORM completions with fewer problems than Presenter?