Front end form can save on custom database?

Hi Long, not sure why frontend submission is not working for me, code below, can you help please ? Doesn´t save on the database nor give confirmation message ....thanks

shortcode [mb_frontend_form id='cliente' confirmation]

metabox code

<?php
add_filter( 'rwmb_meta_boxes', 'your_prefix_register_meta_boxes' );

function your_prefix_register_meta_boxes( $meta_boxes ) {
    $prefix = '';

    $meta_boxes[] = [
        'title'        => esc_html__( 'Cliente', 'text-domain' ),
        'id'           => 'cliente',
        'post_types'   => ['budget'],
        'context'      => 'normal',
        'priority'     => 'high',
        'autosave'     => true,
        'fields'       => [
            [
                'id'    => $prefix . 'post_title',
                'type'  => 'text',
                'name'  => esc_html__( 'title', 'text-domain' ),
                'class' => 'post_title',
            ],
            [
                'id'    => $prefix . 'numero_proposta',
                'type'  => 'text',
                'name'  => "###N\xc3\x9aMERO PROPOSTA###",
                'class' => 'numero_proposta',
            ],
            [
                'id'    => $prefix . 'nome_cliente',
                'type'  => 'text',
                'name'  => esc_html__( 'NOME', 'text-domain' ),
                'class' => 'nome_cliente',
            ],
        ],
        'table'        => 'bdg_tanksbr',
        'storage_type' => 'custom_table',
    ];

    return $meta_boxes;
}

post_type code

function your_prefix_register_post_type() {

    $args = array (
        'label' => esc_html__( 'budgets', 'text-domain' ),
        'labels' => array(
            'menu_name' => esc_html__( 'budgets', 'text-domain' ),
            'name_admin_bar' => esc_html__( 'budget', 'text-domain' ),
            'add_new' => esc_html__( 'Add new', 'text-domain' ),
            'add_new_item' => esc_html__( 'Add new budget', 'text-domain' ),
            'new_item' => esc_html__( 'New budget', 'text-domain' ),
            'edit_item' => esc_html__( 'Edit budget', 'text-domain' ),
            'view_item' => esc_html__( 'View budget', 'text-domain' ),
            'update_item' => esc_html__( 'Update budget', 'text-domain' ),
            'all_items' => esc_html__( 'All budgets', 'text-domain' ),
            'search_items' => esc_html__( 'Search budgets', 'text-domain' ),
            'parent_item_colon' => esc_html__( 'Parent budget', 'text-domain' ),
            'not_found' => esc_html__( 'No budgets found', 'text-domain' ),
            'not_found_in_trash' => esc_html__( 'No budgets found in Trash', 'text-domain' ),
            'name' => esc_html__( 'budgets', 'text-domain' ),
            'singular_name' => esc_html__( 'budget', 'text-domain' ),
        ),
        'public' => true,
        'exclude_from_search' => false,
        'publicly_queryable' => true,
        'show_ui' => true,
        'show_in_nav_menus' => true,
        'show_in_admin_bar' => true,
        'show_in_rest' => true,
        'menu_position' => 2,
        'menu_icon' => 'dashicons-carrot',
        'capability_type' => 'page',
        'hierarchical' => true,
        'has_archive' => true,
        'query_var' => true,
        'can_export' => true,
        'rewrite_no_front' => false,
        'supports' => array(
            'revisions',
        ),
        'rewrite' => true,
    );

    register_post_type( 'budget', $args );
}
add_action( 'init', 'your_prefix_register_post_type' );

Thanks Long, I will try on a fresh wordpress installation... tried already what you told me but didn't work. cheers