Why have my customers disappeared, when trying to add again it says they already exist

Hello there.

There are instances when the browser is full of commonly used page resources, which results in odd behavior like those missing customers in your account. 

Let's try first searching for them in the Find a Customer field. 

If it doesn't show, we can perform some troubleshooting steps to fix this. Let's use a different or private browser to view your account by using either of these shortcut keys to access one:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Shift + N

Then, proceed to the Customer's page to verify. Once it appears, go back to your regular browser and clear its cache. This is done to speed up the process the next time you do a transaction in QuickBooks. Also, an alternative way is to use other compatible browsers.

Additionally, I've attached an article you can utilize to help manage customers in QuickBooks: Add and manage customers in QuickBooks Online.

Feel free to get back to this thread if you have further questions about missing customers. I would be glad to assist you again. Have a pleasant day!