Hello there, @brad-larson.
I'd like to redirect you to the best support available so this gets addressed right away.
Bank transfer payments from your clients can sometimes be rejected due to incorrect information or insufficient funds.
However, I suggest reaching out to our Merchant Service Team. This way, they can investigate further why your clients received an error when paying their invoices with a bank transfer.
In case you need tips and related articles in the future, visit our QuickBooks Community help website for reference: QBO Self-help.
You can always get back to me if you have any other questions. It'll be my pleasure to help you.