Automatic Invoice Generation & Attach to email

Hi, We were using the older version of WooCommerce PDF Invoices, Packing Slips, Delivery Notes and Shipping Labels. Version: 2.6.4. Today we performed a major upgrade to the latest version of WordPress, Woocommerce & your plugin. But now we find that invoice is not automatically generated nor attached to the email.

Enable invoice Yes

Create and email invoice
Create invoice automatically
Processing
Completed
Creates invoices for selected order statuses.
are selected

Attach invoice PDF in order email
is checked.
Invoice in PDF format will be attached with the order email for chosen order statuses.

If we manually click on print invoice or download invoice, then it generates the invoice fine without issue and we can download.

So any reason why automatic invoice generation is not working?

For your info we are using a sub directory installation of wordpress (like sitename /wp) as another plugin had an issue because its a sub folder installation and was fixed by the developer. So just mentioning this point.