QBO bill pay lack of vendor remittance

You can sign up for a free Melio account to sync with QBO as a workaround. You can also get $100 cashback to pay the first bill.

https://quickbooks.intuit.com/learn-support/en-us/reports-and-accounting/bill-pay-can-t-schedule-a-payment/00/1385182

I recognize the importance of having the option in Bill Pay to send a remittance to your vendors, @kneeboarder.

Currently, sending a remittance feature is unavailable for QuickBooks Online (QBO) Bill Pay. In the meantime, I recommend sending your feedback so our developers can consider adding this feature in the future.

Here's how:

1. Go to the Gear icon in the upper-right corner of your screen.
2. Select Feedback under Profile. 
3. Enter your product comments and suggestions.
4. Click Next to submit.

Furthermore, you can check this article to learn more about QB Bill Pay usage: Learn about QuickBooks Bill Pay.

I'll be here if you've got additional questions regarding Bill Pay or any QuickBooks-related queries. Stay safe.