If a webchat has all necessary fields (properly formatted) and still displays the error that not all fields are entered, it is most likely because there are two elements of the webchat embedded into that webpage.
You'll only see the one window but there is a second "incomplete" request being triggered.
The web developer in charge of the website will need to remove any duplicates of our webchat snippet from the page.
You can prove this by opening their webpage locally and click F12 to open the DevTools window.
Select "Elements" and search for "chat-widget-loader" to find a portion of the snippet. If you see the same snippet twice, they need to remove one.
You can also prove it in "Console" (part of DevTools) to show actions and errors.