Hi,
Since the "return URL" setting of your payment method is empty, what you should see on that thank you page is the content of the file plugins/hikashoppayment/authorize/authorize_thankyou.php
That's basically just the text "Thank you for your purchase".
So there are several possibilities:
- You have a translation override on that text and thus it doesn't display.
- You have some CSS which hides that area.
- You might have an override on that thank you page which change the display of the thank you page.
To be able to say more precisely, we would need a backend access and precise instructions to reproduce the issue on your website without having to make a payment (for example, with a 100% coupon, do you still have the problem ?).