Unable to select "Sales" from the Customer pull-down list when creating an invoice.

Hello, abetterweigh.

I would love to help you, but I need more information about your concern. Please tell me more about the drop-down menu you are referring to about sales. Or are you referring to products or something else?
 

Any additional details you can provide would be greatly appreciated. With this information, I can provide you with the best possible solution. Please provide further details or screenshots that help me understand your situation. Have a great day!

From the menu I click "Invoices" then the button"Create Invoice".

The first field on the screen is "Customer", in the drop down list should be "Sales" so that I can record my shop sales for the day. But the drop down list is empty and just contain the words "+ Add new".