Hello, UserAtBK. I appreciate the things you've done so far to fix the issue. We can work together to ensure you can view your payment history and invoices.

The message you encountered, Network error: Response not successful: Received status code 400, usually refers to the inability to process a request due to an issue perceived by the server.

Since you've already tried using an incognito window without success, I suggest using a different supported browser to troubleshoot it. Make sure you have a strong internet connection.

Here are other supported browsers you can use:

• Google Chrome: version 78 or newer
• Mozilla Firefox: version 76 or newer. 
• Microsoft Edge: version 79 or newer
• Safari: version 12 or newer (Mac only)

If the issue continues, it would be best to contact our technical support. Our expert team should be able to assist you in identifying the root cause and provide steps to resolve it. They can also offer a workaround for you to move forward.

To reach our technical team using your QuickBooks Desktop:

1. Go to the Help menu and click QuickBooks Desktop Help/Contact Us.
2. Select Contact Us.
3. Type a short description of your issue in the box provided, then Continue.
4. Sign in to your Intuit account, choose Continue. Pick Continue with my account.
5. You'll receive a single-use code in your email; enter the code and Continue.
6. Hit Have us call you.

For additional reference, you can visit our Help pages. It contains detailed articles that provide comprehensive instructions and guidelines on managing QuickBooks Desktop more efficiently.
 

You can always reach out anytime you require additional help with your invoices or other transactions. I got you, UserAtBK!