Use Grid layout on category pages

Actually, I tested now and realized that though I can pick a category, that category is not being saved. I bet I did something pretty wrong, sorry to botter again. This is what I did:

// Custom query for grid pages
function bento_grid_query() {
	$post_id = get_queried_object_id();
	$bento_grid_query_args = array();
	$post_types = get_post_meta( $post_id, 'bento_page_content_types', true );
	$bento_grid_query_args['post_type'] = $post_types;
	$bento_grid_query_args['post_tag'] = $post_tag;
	$bento_grid_query_args['category'] = $category;
	if ( is_front_page() ) {
		$bento_paged = ( get_query_var('page') ) ? get_query_var('page') : 1;
	} else {
		$bento_paged = ( get_query_var('paged') ) ? get_query_var('paged') : 1;
	}
	$bento_grid_query_args['paged'] = $bento_paged;
	$bento_grid_number_items = get_post_meta( $post_id, 'bento_page_number_items', true );
	if ( ctype_digit($bento_grid_number_items) && ctype_digit($bento_grid_number_items) != 0 ) {
		$bento_grid_query_args['posts_per_page'] = (int)$bento_grid_number_items;
	} else {
		$bento_grid_query_args['posts_per_page'] = get_option('posts_per_page');	
	}
	return $bento_grid_query_args;
}

// Page settings metaboxes
function bento_metaboxes() {
	
	// Define strings
	$bento_prefix = 'bento_';
	$bento_ep_url = wp_kses( 
		'<a href="https://satoristudio.net/bento-free-wordpress-theme/#expansion-pack/?utm_source=disabled&utm_medium=theme&utm_campaign=theme" target="_blank">Expansion Pack</a>', 
		array(
			'a' => array(
				'href' => array(),
				'target' => array(),
			),
		) 
	);
	
	// Callback to display a field only on single post types
	function bento_show_field_on_single() {
		$current_screen = get_current_screen();
		if ( $current_screen->id == 'page' ) {
			return false;
		} else {
			return true;
		}
	}
	
	// Function to add a multicheck with post types
	add_action( 'cmb2_render_multicheck_category', 'bento_render_multicheck_category', 10, 5 );
	function bento_render_multicheck_category( $args = '', $post_category, $category ) {
	    $defaults = array(
	        'show_option_all'   => '',
	        'show_option_none'  => '',
	        'orderby'           => 'id',
	        'order'             => 'ASC',
	        'show_count'        => 0,
	        'hide_empty'        => 1,
	        'child_of'          => 0,
	        'exclude'           => '',
	        'echo'              => 1,
	        'selected'          => 0,
	        'hierarchical'      => 0,
	        'name'              => 'cat',
	        'id'                => '',
	        'class'             => 'postform',
	        'depth'             => 0,
	        'tab_index'         => 0,
	        'taxonomy'          => 'category',
	        'hide_if_empty'     => false,
	        'option_none_value' => -1,
	        'value_field'       => 'term_id',
	        'required'          => false,
	    );
	    wp_dropdown_categories( 'show_count=1&hierarchical=1' );
	    /**
	     * Filters the taxonomy drop-down output.
	     *
	     * @since 2.1.0
	     *
	     * @param string $output HTML output.
	     * @param array  $r      Arguments used to build the drop-down.
	     */
	}

The metabox field doesn’t save the category value because it’s not being handled correctly – please see CMB2 documentation for examples of taxonomy multicheck implementations.