Hi petermac1,

Appreciate you reporting the behavior encountered on the dates when using the QuickBooks Online mobile app. Since you've done the basic troubleshooting on the mobile app and the issue persists on the app for multiple users, we'd recommend contacting our Customer Care Team so they can escalate the unexpected behavior you've encountered. Since this is a public forum and we're unable to view and verify your account.

In the meantime, you can manually edit the due date on the iPad or login on a web browser to create an invoice. 

Feel free to message us back if you have any other questions. Thanks.