Since the Invoices are coming from Shopvox, I recommend contacting their customer support team to see if they're having issues when importing Invoices to QuickBooks. To get in touch with their support team, you can follow these steps:
Go to the Apps tab.
Search for Shopvox and click it.
Look under App Information for their support info.
You can also go through the website you downloaded the app from and get in touch with an agent there.
Feel free to let me know how the conversation goes below. I'm always here to help.