Hi there, LarryLewis24. 

I'm here to guide you to the right support so you can save your backup file successfully in QuickBooks Desktop (QBDT).

Also, I'd appreciate you're effort in trying all the possible troubleshooting steps to fix this issue. Since the issue persists, I suggest contacting our Customer Care Team. This way, they can check into your account in a secure environment and investigate further about the issue.

Here's how to reach them:

1. Open QuickBooks Desktop.
2. Go to the Help menu, then select QuickBooks Desktop Help.
3. Click Contact Us at the bottom.
4. Enter a brief description of your issue, then select Let's Talk.
5. Choose a way to connect.

To make sure you get prioritized on your concern. Please check out our support hours and contact us at a time convenient: Support hours and types.

Moreover, you’ll want to check out this article to restore a backup of your company file: Restore a backup of your company file

Stay in touch if you have more concerns about your backup file. The Community will surely assist you with this. Stay safe!

When it was working properly, the file was saved to a Quickbooks Company Backup fole format (.qbb)

When it was working properly, the backup file was in the Quickbooks Backup File Format (,qbb). Now it it is leaving a temporary file that doesn't work.