We've recently added a new toggle at the top of your Customers page. When the toggle is turned on it will show ALL customers assigned to you and shared with you. When the toggle is turned off it is only showing customers assigned to you.
It's important to note that this could be why you are not seeing all of your customers. We've added this feature as many users look after customers that are not assigned to them but still need visibility over those accounts.
If you are having trouble viewing your customers, please reach out to our support team at: support@numerik.ly.