滑块窗口中的项目在使用inspect元素之前不显示

The items in the "Accessories" pane are not displayed upon loading in the PrestaShop web site we developed. The height of the element (pane) shows 0px.

However, once the "Inspect element" function in Firefox or "inspect" in Google Chrome is used, all items appear in the Accessories window correctly.

Yet they disappear again if the page is reloaded or refreshed! Does anybody know how to solve the problem?

Below are the links to sample pages:

http://www.filterdepot.ca/index.php?id_product=8&controller=product

http://www.filterdepot.ca/index.php?id_product=78&controller=product