PHP function not saving invoice correctly

Hi WP-Invoice,

I have just started using your plugin in a project where I have run in to an issue.

I am trying to programmatically create an invoice. The thing is, that I can get it to save the invoice, so it shows up in the control panel with all credentials, line items etc. correctly. But it does not send the notification e-mail automatically. Why is that? I have attached my current code.

$invoice = new WPI_Invoice();

// Set defaults
$invoice->load_defaults();

// Set user
$user_args = array(
	'email' => $email,
);

$invoice->load_user( $user_args );

// Create the invoice
$invoice_args = array(
	'subject' => 'Subject title',
	'description' => 'Description'
);

$invoice->create_new_invoice( $invoice_args );

// Add a line item
$line_item_args = array(
	'name' => 'Some name',
	'description' => 'Some description',
	'quantity' => 1,
	'price' => '2500',
	'tax_rate' => '25'
);

$invoice->line_item( $line_item_args );

// Set due date
$invoice->set("due_date_day=" . $day); // day
$invoice->set("due_date_month=" . $month); // month
$invoice->set("due_date_year=" . $year); // year

// Set type
$invoice->set("type=invoice");

// Save invoice to database
$invoice->save_invoice();

Also there is some weird behavior when opening the individual invoices. I do not get the option to send notifications or view the invoice on frontend before I have pushed the “Save”-button.

Here is two screenshots of a before/after pushing “Save”-button.
Before save
After save

https://ww.wp.xz.cn/plugins/wp-invoice/