between column groups is not showing on mobile

Hi there, I am inserting a horizontal rule in between clusters of the columns and the line shows when viewing on my desktop, but disappears when resized for mobile.

This is what my code looks like:

<h5 style="line-height: 1.2em;">Inc Magazine | June 28, 2018</h5>
<h4 style="line-height: 1.2em;"><a href="https://www.inc.com/robert-glazer/this-group-has-figured-out-how-to-teach-kids-entrepreneurship-you-can-learn-from-it-too.html" target="_blank" rel="noopener">This Group Has Figured Out How to Teach Kids Entrepreneurship. You Can Learn From It, Too</a></h4>
[lgc_column grid="20" tablet_grid="20" mobile_grid="30" last="false"]<a href="https://www.inc.com/robert-glazer/this-group-has-figured-out-how-to-teach-kids-entrepreneurship-you-can-learn-from-it-too.html" target="_blank" rel="noopener"><img class="aligncenter size-thumbnail wp-image-5644" style="width: 100%; margin: 0;" src="https://www.buildinboston.org/wp-content/uploads/2018/06/getty_603298882_361799-150x150.jpg" alt="Inc. Magazine" /></a>[/lgc_column]

[lgc_column grid="80" tablet_grid="80" mobile_grid="70" last="true"]<em>American students have years of history, English, and calculus lessons--yet they have had no hands-on, experiential learning to prepare them to compete in the workforce.</em>[/lgc_column]

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<h5 style="line-height: 1.2em;">CBS Boston | February 23, 2018</h5>
<h4 style="line-height: 1.2em;"><a href="https://boston.cbslocal.com/2018/02/23/ayele-shakur-build-greater-boston/" target="_blank" rel="noopener">BUILD Gives Boston Students Tools To Become Entrepreneurs</a></h4>

[lgc_column grid="20" tablet_grid="20" mobile_grid="30" last="false"]<a href="https://boston.cbslocal.com/2018/02/23/ayele-shakur-build-greater-boston" target="_blank" rel="noopener"><img class="aligncenter size-thumbnail wp-image-5644" style="width: 100%; margin: 0;" src="https://www.buildinboston.org/wp-content/uploads/2018/02/CBS-AYele-150x150.png" alt="CBS News" /></a>[/lgc_column]

[lgc_column grid="80" tablet_grid="80" mobile_grid="70" last="true"]<em>Boston is a hub of economic activity, but not always opportunity, which is where Ayele Shakur comes in.</em>[/lgc_column]

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I’ve also tried wrapping the h4 and h5 headlines in a shortcode for a 100% column and got the same result.

I’d appreciate any help you can offer!

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