Hello armourlocksmiths,

It's good to know you've done some troubleshooting steps to isolate the unexpected behavior encountered when using the QuickBooks Online mobile app. 

There is a reported product investigation with iOS Unable to log in using the mobile app. No error it simply crashes in QuickBooks Online. I'd recommend contacting our Customer Care Team. That way, one of our customer care can check if this is the same issue you've encountered, and they can add your company details for further investigation.

In the meantime, we recommend using the web version while the issue is being worked on. Here's the link: https://quickbooks.intuit.com/au/.

Post again if you need anything else. Have a nice day!