Mine is very similar. I am running WordPress with Mailchimp. If name is required, I get an error message from Mailchimp that the name field is blank when its not blank. If the name is entered in the name field on the error message screen by Mailchimp, the name is captured. However, if the name is not required, there’s no error message from Mailchimp, but the name is not captured by Mailchimp, even when the name is entered on the Optin Form.
It appears that Optin Form is not currently capturing the name field.