Recover a module that no longer appears in the PrestaShop theme

If a block stops showing without a visible error, first check its current state in Design > Positions. It may be missing because it lost its hook, but also because the module is disabled, has an exception for that page, does not generate content, the theme does not run the hook or the block is hidden with CSS.

In the example, the ps_languageselector language selector had disappeared from the navigation bar.

1. In Design > Positions, search for the module's technical name and check its active hooks and their exceptions.
2. If you need to know the intended position when the theme is activated, check /themes/Nombre_Plantilla/config/theme.yml. This file does not necessarily reflect the live positions of a theme that is already active.
3. Check in the templates that the corresponding hook is run. In the PrestaShop 1.7 Classic theme, for example, ps_languageselector is set on displayNav2, not on displayNav.
4. Check that the module is enabled and that the element is not present in the HTML but hidden by styles.

If the active position does not contain the module and the theme does run that hook, use Transplant a module, then select the module and the verified position.

Clear the cache and check the same page. If the module is listed in the position but does not appear, do not transplant it again: check its exceptions, the module output, the theme hook and the PrestaShop logs.

See the official documentation on hooks and module positions.

Check context, order and duplicates

In multistore, check which shop you are editing before changing positions. Note the previous order and exceptions so you can restore them. A module can be attached to several hooks; adding it to another without checking its output can duplicate the block.

After transplanting it, test the same page, other pages with exceptions and the mobile view. If there are several languages, check that the module has content for the affected language. Do not reset or reinstall the module as a first step: those actions can change its configuration as well as its positions.