Hi Andre,
Thanks for your reply. This is the message I got back from my Theme support team:
Walker_Nav_Menu is a core class used to implement an HTML list of nav menu items ( more info here ).
Bridge theme extends it and the implementation is done in the following files:
wp-content\themes\bridge\includes\nav_menu\edit_custom_walker.php
wp-content\themes\bridge\includes\nav_menu\qode-menu.php
We haven’t tested the ‘If Menu’ plugin with Bridge and it’s not officially supported. The integration of third-party plugins requires custom coding and it’s not covered by our support service. My advice is to contact the plugin support. If they are not able to help, please consider using some other plugin for this purpose.
Is the only option to try another plugin?