<?php
//add_filter( 'woocommerce_bacs_process_payment_order_status','filter_process_payment_order_status_callback', 10, 2 );
//add_filter( 'woocommerce_cheque_process_payment_order_status','filter_process_payment_order_status_callback', 10, 2 );
//function filter_process_payment_order_status_callback( $status, $order ) {
//    return 'processing';
//}

add_action( 'woocommerce_thankyou_bacs', 'bacs_order_payment_processing_order_status', 10, 1 );
function bacs_order_payment_processing_order_status( $order_id ) {
    if ( ! $order_id ) {
        return;
    }

    // Get an instance of the WC_Order object
    $order = wc_get_order( $order_id );

    if ( in_array( $order->get_status(), array('on-hold', 'pending') ) ) {
        $order->update_status('processing');
    } else {
        return;
    }
}