Why have some customers in my customers and leads started vanishing on their own?

Hey there Mathnasium of Brantford,

Thanks for reaching out to us here. We're always happy to see new faces!  Making sure you're seeing all of your customers and leads is important. I would be happy to provide some information.

It may be browsing data on your system that is preventing the software from doing what it is supposed to do. Here are some steps to resolve issues that are caused by browsing data:
 

• Clear your browser cache if you're using a browser
• Try a browser if you're using the app
• Try a private browser window
• Try another browser type
• Make sure you're using a supported browser and system
• Reset your Internet or try on another computer or device
• Uninstall the QuickBooks Online App, and re install it.

If you're still unable to see your customers, I recommend reaching out to the support team outside of the Community. They'll be able to verify your account details in a secure setting, as well as view your screen to better assist you. They also have the necessary tools to create a ticket to get the issue resolved if they see fit. You can reach them by following one of these methods:

Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.
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If you have any other questions, feel free to reach out here.