All customers gone and invoices

We're glad to see you posting here in the Community forum, Mark. Let's work together in resolving your customer and invoice concerns in your QuickBooks Online account.

As I've checked my resources here, there are no reports relating to your concern. Sometimes a browser is loaded with frequently accessed pages, which results in some unusual behaviors. With that, let's perform some troubleshooting steps to rule out the possibility of a webpage issue. 

To begin, you'll need to access your QBO account in a private browser. Doing so will allow the program to run without storing cache files that can cause problems when running Intuit sites. You may use these keyboard shortcuts:

• For Google Chrome browser: Ctrl + Shift + N
• For Mozilla Firefox browser: Ctrl + Shift + P
• For Safari browser: Command + Shift + N

If your QuickBooks runs smoothly from there, you may return to your default browser and clear its cache or use a different supported browser. This may be a temporary issue with the browser you're using.

Additionally, you can check out your Audit Logs to review if there are any unusual changes made to your account. It would help you track what changes were done and who changed them.

Moreover, I've added this article to guide you in reviewing your company's finances and other specific reports to track your business data: Run reports in QuickBooks Online.

We'll always be here anytime you need assistance managing your customer and invoices, Mark. Please don't hesitate to reply in the comments below if you have additional questions. Keep safe and have a great day!