Mailchimp does not auto sync first/last names

I know this question has been asked but I have tried the other solutions without success.

All new registered users' emails are autosyncing to my mailchimp list but the first/last names are not.

I can manually sync the list but this is not a preferred solution.

Using Buddypress (syncing w/ BP -> WP is enabled) Both first and last name are on the "base" group

Can anyone help?