I had a similar issue. Calling QB support was useless. I was on the phone for over 90 minutes and they just didn't comprehend my issue.

Seems to me that you may have had encrypted credit card data stored in a customer that you deactivated. That's my story. Out of 478 errors, I only have 471 to go...

Rebuild your file and view the results. Click/expand error 310. Print that list. Next, export your customer list to an .iff file and open it in excel. Search for the customer ID from the error list in the spreadsheet. Get the customer name. Find the customer name in QB customer list. Go to payment settings and enter a dummy credit card number. Click Save.

I did that for 5 customers and the errors were reduced by 5. 

Let me know how it goes!