'There is a connection issue' error when a chat is initiated via Embedded Service (formerly Snap-ins)

1. Ensure the website with Embedded Service is added on CORS list in Salesforce Setup.
2. Verify none of the fields available in the Chat Transcript are marked as required.
3. Confirm that the prechat form fields do not have identical labels to other fields, since labels are mapped for prechat instead of the field API name. 
4. Check that the chat button does not have a prechat form value set within the button settings. Prechat forms for Embedded Service are only supported within the Embedded Service deployment.