CMB2 - Cannot have two taxonomy_* fields.

<?php
add_action( 'cmb2_admin_init', 'diabolo_home_page_listings' );
function diabolo_home_page_listings() {
    $prefix = '_dp_';

    $cmb = new_cmb2_box( array(
        'id'           => $prefix . 'metaboxID',
        'title'        => 'Column 2 & 3 Settings',
        'object_types' => array( 'page' ),
        'context'      => 'after_editor',
        'show_names'   => true,
        'show_on_cb' => 'diabolo_show_cmb2_on_front_page',
    ) );

    $cmb->add_field( array(
        'name'    => 'Column 2 title',
        'desc'    => 'Enter the text to be shown above the posts in column 2.',
        //'default' => 'standard value (optional)',
        'id' => $prefix . 'col2title',
        'type'    => 'text',
    ) );
    $cmb->add_field( array(
        'id' => $prefix . 'col2category',
        'type' => 'taxonomy_radio',
        'taxonomy' => 'category',
        'name' => 'Column 2 category',
        'desc' => 'Select the category for posts in column 2',
    ) );
    $cmb->add_field( array(
        'name' => 'Number of posts to show',
        'desc' => 'Numbers only',
        'id'   => $prefix . 'col2count',
        'type' => 'text',
        'attributes' => array(
            'type' => 'number',
            'pattern' => '\d*',
        ),
    ) );
    $cmb->add_field( array(
        'name'    => 'Column 3 title',
        'desc'    => 'Enter the text to be shown above the posts in column 3.',
        //'default' => 'standard value (optional)',
        'id' => $prefix . 'col3title',
        'type'    => 'text',
    ) );
    $cmb->add_field( array(
        'id' => $prefix . 'col3category',
        'type' => 'taxonomy_select',
        'taxonomy' => 'category',
        'name' => 'Column 3 category',
        'desc' => 'Select the category for posts in column 3',
    ) );
    $cmb->add_field( array(
        'name' => 'Number of posts to show',
        'desc' => 'Numbers only',
        'id'   => $prefix . 'col3count',
        'type' => 'text',
        'attributes' => array(
            'type' => 'number',
            'pattern' => '\d*',
        ),
    ) );
}

function diabolo_show_cmb2_on_front_page( $cmb ) {
    //error_log( "CMB: ".var_export( $cmb, true ) );

    // Extracted from: https://github.com/CMB2/CMB2/wiki/Adding-your-own-show_on-filters#example-front-page-show_on-filter
    $post_id = 0;

    // If we're showing it based on ID, get the current ID
    if ( isset( $_GET['post'] ) ) {
        $post_id = $_GET['post'];
    } elseif ( isset( $_POST['post_ID'] ) ) {
        $post_id = $_POST['post_ID'];
    }

    if ( ! $post_id ) {
        return false;
    }

    // Get ID of page set as front page, 0 if there isn't one
    $front_page = get_option( 'page_on_front' );

    // There is a front page set and we're on it!
    return $post_id == $front_page;
}