shortcode content always appears above other content even if it's not

In file “shortcodes.php” inside this function “sell_media_all_items_shortcode” it echo’s the content immediately. Is there any way to change this so I can put other content at the top of the gallery page? Currently my custom content always appears at the bottom, no matter what. Even if I try to use a page layout plugin to put the gallery at the bottom. Doesn’t work.

Reference:
https://www.ads-software.com/support/topic/shortcode-output-always-appearing-at-top-of-page-content

https://www.ads-software.com/plugins/sell-media/