Missing graphics

Dear fellow Articulate-fans!

I am a huge fan of Articulate, but I am experiencing a reoccuring problem that keeps me up at night.
Sometimes my users experience missing graphics in the e-learning course. It is always interactive elements (buttons, drag 'n drop graphics, player-buttons like Next and Submit and similar) that do not show up, which causes that the user cannot continue the course. Extremely frustrating.

(Please see my examples below taken from three totally different courses.)

The big mystery is that this problem with missing graphics occurs in:

• totally random courses (has happened sporadic in over 5 courses)
• happens in completely different places/slides in the courses
• happens for both PC, Mac and iPad
• happens in different browsers, but mostly Internet Explorer and Mobile Safari,
• happens for users in US and Europe (great bandwidth) and in China (poor bandwidth)

The only current solution is to ask the user to exit the course, enter it again and click "Resume progress". When doing so, the course starts where the user left off, and all graphics are now loaded and shown perfectly. This is of course not acceptable to ask them to, so there must be another solution.

When I sent this issue to Articulate support, who could not replicate the issue, I was told the following:
"Since you mentioned the issue is sporadic and happens in multiple files then it is likely a quick glitch on the browser, or a disruption on the user’s Internet connection which disables each of the objects to be downloaded properly."
This was followed by a long guide on how to upgrade flash player, clear cache, reset browser to default, delete content in (...)\Macromedia\Flash Player\#SharedObjects" etc.
None of this helped and is of course not something I expect my thousands of users worldwide to do before taking each course.

I experience this problem when publishing my .storyline-file to my Articulate Online account, and I am starting to suspect that the problems occurs here. As I recall I do not experience the problem, when publishing to CD, my LMS or the tempshare.articulate.com. 

Details:
Yes - I am using the latest update of Storyline. (Update 2)

I have tried to output my .story-file from both PC and MAC

I have tried to disable and enable html5 (the problem does not occur when using the Mobile Player App)

I have tweaked the output settings quality with no success.

I have of course made sure that the "timing" on each object is shown "to the end of timeline".

So my question is:

Have you experienced this problem with missing graphics before?

Thank you very much for your comments and inputs.