Favicon.ico issue with LMS

Hi all,

I have created 2 training courses with Articulate Storyline 360 for a client using Cornerstone On Demand as LMS.
The courses have been exported under SCORM 2004 3rd Edition.
Before implementation in Cornerstone, I have performed many tests with no reported issues in Scorm Cloud website. The client has also performed many tests with success before assigning all the employees to the courses. Based on these successfull tests, the courses have been assigned.

Unfortunately, some employees (not all of them) have issues : they are blocked during the course: Cornerstone displays this message "Failed to load resource : the server responded with a status of 404 ()" /favicon.ico:1 (see printscreens in attachment)
After some investigations, I have added a "blank" favicon.ico in the SCORM package to fix the issue : it fixes the issue only for some concerned employees.

Has anyone come across this problem before ?

Many thanks for your precious help :-)

Cécile Roy