HTML5 Output from Storyline 2 Update 4

I'm having issues with the html5 output of courses displaying - none of the slide contents appear, and the player is blank. I believe this is a bug that was resolved in Update 5, but because I work in a locked-down network, it's costly and time-consuming to request an updated version of SL2. So my question is, is there another fix to the html5 output that I can make, or do I have to upgrade? 

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