Hello there, Tammy111.

I can see that you've posted twice with the same concern about viewing an invoice on this thread: https://quickbooks.intuit.com/learn-support/en-us/reports-and-accounting/re-why-is-customer-is-not-g.... 

As I've checked our records, I found out that we received a report from other users about Invoice unavailable when trying to view PDF copy sent with E-invoice when access on iOS Mobile Device. Right now, our Product Engineers are working to fix it as quickly as possible. While they do, I recommend reaching out to our Customer Care Team, so you'll be added to the list of affected users and receive email updates. 

To reach them, click the ? Help button at the top-right corner and select Contact Us to talk with a live agent. Ensure to review their support hours to know when agents are available.

I appreciate your patience while we work for a fix. If you have additional assistance while managing your QuickBooks account, let me know. I'll be around to provide further assistance. Have a nice day.