It's important you're able to save your invoices so you have a record of them on your account. I'll be glad to give you a hand with troubleshooting the issue.
To troubleshoot this, I recommend clearing cache and cookies to determine if this is a browser issue. If the issue persists after clearing cache and cookies, I suggest calling our phone support experts by dialing 1-855-253-1536. The hours of operation are Mon - Fri 9 AM - 8 PM EST and SAT 9 AM - 6 PM. One of our experts will be able to share your screen and take a closer look at what's happening. Let me know if you have questions. I'll be here in case you need anything.