Storyline Loading 'Throbber' doesn't show before first slide

Hello all. I have a rather heavy project where I'm using a lot of objects with multiple PNGs imported as states, and I ran across an issue where those states weren't showing up when they were called right away.

I figured it's because those PNGs weren't loaded yet, so I put copies of those objects on an extra layer in the master slide to make sure they are loaded into the cache as soon as possible. It works quite well, and prevents the issue with the states. 

What I'm interested in though, is that the usual 'Throbber' animation of the three-dots loading before a slide, doesn't happen. I see it a lot when a slide with a long video is loading up, and you wait until everything is loaded before the slide plays.

I'd expect the same behaviour when loading all these PNGs in the background. The slide isn't ready yet, show the throbber. But it doesn't show, and instead just shows a blank player for a few seconds, which I worry may give the end user the impression that the browser is frozen or something.

I'm wondering if there is a way I can force the loading 'throbber' to show up before the first slide starts, or perhaps if there is a way I can easily add my own loading animation to the course, without adding it to a slide. As, like I said, I don't believe the slide is actually loaded yet, so putting my own loading animation ON the slide, I think would be pointless.

Thanks!