Thanks for getting back to us and performing the troubleshooting steps shared by my colleague, Michele67a.

Usually, clearing the browser cache and accessing QuickBooks Online to a supported browser can help verify and rectify the error message. 

Since the issue persists, I recommend contacting our phone or chat support team. They have tools to investigate the cause of this and provide additional solutions to fix the problem. I've included the steps to contact support below. 

1. Go to the Help (?) icon at the top.
2. On the Assistant tab, click Talk to a human.
3. Enter "unable to process scheduled payment" in the Type something field, then click the Send icon.
4. Click on I still need a human.
5. Select Get help from a human.
6. You can either select Chat with us or Have us call you.
   

I appreciate your patience as we work through this. If you have any other concerns or questions about managing your vendor transactions, please don't hesitate to add a comment below. I'll be glad to help you out.