Div Line Only Appears Sometimes

Hi,
We run a products website using wordpress and the page-builder plugin.
In the past, I have seperated our products using a handy little code that creates a nice responsive tapered line that I found somewhere on the web.
<div class=”sexy_line”></div>

However, the lines have started becoming erratic, and only seem to show up when they feel like it, even when their code is copy>pasted from another text box, and shows up just fine there.

Our website is https://www.outwestsaddlery.com
you can see the correct div lines on our testimonials page: https://outwestsaddlery.com/custom-horse-gear
—where they appear between every paragraph. Most of the time they work fine, but lately, on some of our pages, they only appear in certain areas, instead of in all the places we wrote them in.
What is wrong?!
Thanks!