Having similar issue with the invoice links.

I am not.  I am using the Shopify graphql api.  Thank you though for responding! 

Hello!Has anyone had issues with the email invoice API endpoint not working for certain email domains?  The logs in the UI says that the email was sent but my customer and the CC to my email never is received. But when I send them through the UI, the...

Yes, we are too when using the invoice payment links. I have talked with support and they are escalating the issue. Not sure what exactly is the issue, but we were getting 429 errors when we try to submit a payment.

they are now back up

I am having the same issue.  Also CC payment option is not showing up on the invoice link.