Allow PageBuilder to see your custom fields

functions.php

function register_unique_namespace( $class_prefixes = array() ) {
    $class_prefixes[] = 'My_Custom_Field_';
    
    return $class_prefixes;
}
add_filter( 'siteorigin_widgets_field_class_prefixes', 'register_unique_namespace' );

function register_my_custom_fields_folder( $class_paths = array() ) {
    $class_paths[] = dirname( __FILE__ ) . '/fields/';
    
    return $class_paths;
}
add_filter( 'siteorigin_widgets_field_class_paths', 'register_my_custom_fields_folder' );