Hello James Bukowski
Please help me find and open file: modules/mod_jo_responsive_grid_gallery_articles/tmpl/default.php
and go to line 113 and change (<?php echo $item->imageMedium?> to <?php echo JUri::root().$item->imageMedium?>)
<div class="mega-entry cat-all cat-<?php echo preg_replace('/\s+/', '', $item->category_title)?>" id="mega-entry-<?php echo $item->id?>" data-src="<?php echo $item->imageMedium?>" data-width="504" data-height="400">
To
<div class="mega-entry cat-all cat-<?php echo preg_replace('/\s+/', '', $item->category_title)?>" id="mega-entry-<?php echo $item->id?>" data-src="<?php echo JUri::root().$item->imageMedium?>" data-width="504" data-height="400">
Or can you send me joomla administrator via contact form? So we can help you
Best regards
Bach Pham