Reminder Invoice - Payment link NOT Working

Reminder Invoice - Payment link NOT Working

Hello,
 
I have found ALL my automated reminder emails have an issue with the "Make payment via PayPal" link.
 
When clicking on the link in an email, the customer ends up at Zoho Invoice sign in page.
 
Looking at the link code, and comparing it with the code in an invoice sent before the reminder, I found ":443" to be missing and replaced by an extra"/" after https://invoice.zoho.com
 
However, manual reminders, DO NOT have this issue.
 
Please could someone help with this?
 
VIP Group Online