$@ = '';
eval {
    $order = TblOrders->find_or_create(
                order_id => $order_values->{order_id},
    );

    [... update columns here ...]

    $order->update; # THIS WORKS
};
confess "Could not update order: $@\n" if ($@);

# THIS NEXT BIT FAILS
$order = TblOrders->retrieve($order_values->{order_id})
    or confess "Could not read back order with "
    . "order ID = $order_values->{order_id}\n";

##</code><code>##

sub store_order {
    my ($self) = @_;

    my $order_values = $self->prepare_data_for_database("orders");

    my $order;

    if ($order_values->{order_id}) { # Replace an existing order
        $@ = '';
        eval {
            $order = EN::OrdersDB::Orders->find_or_create(
                order_id => $order_values->{order_id},
            );

            # Update the fields of the object
            foreach my $field (keys %$order_values) {
                $order->$field($order_values->{$field});
            }
            $order->update; # Update the database
        };
        confess "Could not update order: $@\n" if ($@);

        # THIS NEXT BIT FAILS
        $order = EN::OrdersDB::Orders->retrieve($order_values->{order_id})
            or confess "Could not read back order with "
                       . "order ID = $order_values->{order_id}\n";
    }
    else { # Insert a new order
        [ ... code to insert new order ... ]
    }
    return $order;
}