Make the slug of the parent menu item and sub-menu same (first one item) as below
function actions_recent_bids_add_admin_page(){
add_menu_page(
'Recent Bids',
'Auction Reports',
'manage_options',
'wc-auction-reports',
'actions_recent_bids_list',
'dashicons-chart-area',
56
);
add_submenu_page(
'wc-auction-reports', // parent slug
'Recent Bids', // page title
'Recent Bids', // menu title
'manage_options', // capability
'wc-auction-reports', // slug
'acutions_customers_spendings_list' // callback
);
add_submenu_page(
'wc-auction-reports', // parent slug
'Customer Spending', // page title
'Customer Spending', // menu title
'manage_options', // capability
'wc-acutions-customers-spendings', // slug
'acutions_customers_spendings_list' // callback
);
add_submenu_page(
'wc-auction-reports', // parent slug
'Customer Bids', // page title
'Customer Bids', // menu title
'manage_options', // capability
'wc-acutions-customers-bids', // slug
'acutions_customers_bids_list' // callback
);
}
add_action('admin_menu','actions_recent_bids_add_admin_page');