Hello, benfleetcounsell.  

Thank you for reaching out to the Community. There are possible reasons why Direct debit fails to collect. When a Direct Debit payment fails, as a service user, you’ll receive a notification via an ARUDD (Automated Return of Unpaid Direct Debit) report, citing a reason for the failure. The most common reasons are insufficient funds or where a payer has canceled their instruction. Other reasons include:  

• The account has been closed, transferred or is not recognized
• There is a dispute from the payer, such as the amount or due date
• There is no Direct Debit Instruction in place.

In this case, I suggest reaching out directly to Direct debit to check why it's not been collected by go cardless. See this link on how to reach them: Go Cardless Suppor.  

To learn more about how Go Cardless work in QBO, consider checking out this article: Learn more about GoCardless Direct Debit for QuickBooks. 

Feel free to visit again if you have additional questions. I'm always delighted to help you some more. Take care!