Line spacing not working in responsive project

I'm building a responsive course in Captivate 8, and my text is always set to a line spacing of 1.6.

In Captivate, it looks fine, but in the preview and published outputs the first two lines are noticeably closer together than the other lines. This happens consistently throughout the entire project. It doesn't matter what font it is, whether it's in a text caption or smart shape.

I looked at my other responsive projects, and it seems to happen intermittently there.

I've tried retyping the text, creating brand new smart shapes for the text, copying it into notepad and then pasting back into Captivate, nothing's worked yet.

Does anyone know what causes this and how to fix it?

I've included a picture below, on the left is my Captivate, as you can see the line spacing is even. But on the right, in the browser, it's smaller on top and bigger below.

Thanks in advance!