Hello,

We would like to apologize for the trouble.

The issue of the customizer is very unlikely to happen and also the additional code must be added through the child theme to avoid the loss of changes.

The data that you have added won’t be deleted upon switching but the customizer setting might require resetting and it completely depends on the theme.

However, we do have the code using which you can bring the parent customizer setting to the child. So add below-given code in your child theme functions.php file.

function travel_master_pro_child_update_option_vals( $value, $old_value ) {
      update_option( 'theme_mods_' . get_template(), $value );
      return $old_value; // prevent update to child theme mods
 }
function travel_master_pro_child_customizer_default_vals_update( $default ) {
     return get_option( 'theme_mods_' . get_template(), $default );
 }
function travel_master_pro_child_customizer_parent_options_import() {
if ( get_stylesheet() !== get_template() ) {
 add_filter( 'pre_update_option_theme_mods_' . get_stylesheet(), 'travel_master_pro_child_update_option_vals', 10, 2 );
 add_filter( 'pre_option_theme_mods_' . get_stylesheet(), 'travel_master_pro_child_customizer_default_vals_update' );
}
}
add_action('init', 'travel_master_pro_child_customizer_parent_options_import');

Also, turning back to the parent theme won’t generate the issue as you have reported. So if you have installed any third-party plugin then please deactivate them and verify the issue.

Hope this helps.

If you have further confusion, let us know.

Regards.

Hello,

Also, add CSS we provided to you in the Additional CSS of customization section.

Hope this helps.

Regards.