This client of yours was on pay-by-refund?

Are you signed up for the IRS E-newsletters? Are you using their resources:

https://www.irs.gov/coronavirus/second-eip-faqs

They have FAQs for things like "status not available" and other issues that tell you what this means.

"Is there something that can be done to correct this?"

If it is the same error as Turddotaxx and Block customers, sounds like you used a banking product.  So to correct it, you could always write them a check until they get their credit.  Kinda show them how much you appreciate their business.