Mailchimp List not Updating

Hi,

I am doing some local MAMP Pro testing of the new Mailchimp app. I have a simple signup form:

<div class="newsletter-sub">
<perch:form id="subscribe" app="perch_mailchimp" double-optin="false" class="signupform">
<perch:success>
    <p>Thank you!</p>
</perch:success>
    <div>
        <perch:label for="email">Sign Up for our Newsletter</perch:label>
        <perch:input id="email" required="true" type="email" mailer="email" placeholder="Enter your Email Address" />
        <perch:error type="required" for="email">Required</perch:error>
    </div>
    <div>
        <perch:input type="submit" value="Submit" id="btnsubmit" />
        <perch:input type="hidden" value="1" id="confirm" mailer="confirm_subscribe" />
        <perch:input type="hidden" id="list" value="d7d3a95a63" mailer="list" />
    </div>
</perch:form>
</div>

When I fill it in I get the success message, and debug shows Subscribing to: Newgate Clocks which is correct. However the new email is not showing in either Mailchimp or Perch. The API Key is correct, I am not sure what else I need to do. There is this array under the subscribing message which looks like an error but I am not sure:

Array
(
    [headers] => Array
        (
            [url] => https://us12.api.mailchimp.com/3.0/lists/d7d3a95a63/members
            [content_type] => application/problem+json; charset=utf-8
            [http_code] => 400
            [header_size] => 417
            [request_size] => 413
            [filetime] => -1
            [ssl_verify_result] => 0
            [redirect_count] => 0
            [total_time] => 0.901968
            [namelookup_time] => 0.395512
            [connect_time] => 0.395902
            [pretransfer_time] => 0.734015
            [size_upload] => 79
            [size_download] => 259
            [speed_download] => 287
            [speed_upload] => 87
            [download_content_length] => 259
            [upload_content_length] => 79
            [starttransfer_time] => 0.901865
            [redirect_time] => 0
            [redirect_url] => 
            [primary_ip] => 104.82.214.148
            [certinfo] => Array
                (
                )

            [primary_port] => 443
            [local_ip] => 192.168.100.44
            [local_port] => 64242
            [request_header] => POST /3.0/lists/d7d3a95a63/members HTTP/1.0
Host: us12.api.mailchimp.com
User-Agent: DrewM/MailChimp-API/3.0 (github.com/drewm/mailchimp-api)
Accept-Encoding: deflate, gzip
Accept: application/vnd.api+json
Content-Type: application/vnd.api+json
Authorization: apikey 96f550754104cd3a3041562bf6adf0e4-us12
Content-Length: 79


        )

    [body] => {"type":"https://developer.mailchimp.com/documentation/mailchimp/guides/error-glossary/","title":"Invalid Resource","status":400,"detail":"The resource submitted could not be validated. For field-specific details, see the 'errors' array.","instance":"","errors":[{"field":"merge_fields","message":"Schema describes object, array found instead"}]}
)

This is my diagnostics summary:

SUMMARY INFORMATION

Perch Runway: 2.8.29, PHP: 5.6.10, MySQL: mysqlnd 5.0.11-dev - 20120503 - $Id: 3c688b6bbc30d36af3ac34fdd4b7b5b787fe5555 $, with PDO
Server OS: Darwin, apache2handler
Installed apps: content (2.8.29), assets (2.8.29), categories (2.8.29), perch_forms (1.8.3), perch_shop_orders (1.0), perch_shop_products (1.0), perch_shop (1.0.1), perch_members (1.5), perch_mailchimp (3.0)
App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_forms', 'perch_members', 'perch_shop', 'perch_mailchimp' );
PERCH_LOGINPATH: /admin
PERCH_PATH: /Volumes/Data/g Websites/New Development/Newgate/CLOCKS FINAL 2/admin
PERCH_CORE: /Volumes/Data/g Websites/New Development/Newgate/CLOCKS FINAL 2/admin/core
PERCH_RESFILEPATH: /Volumes/Data/g Websites/New Development/Newgate/CLOCKS FINAL 2/admin/resources
Image manipulation: GD
PHP limits: Max upload 128M, Max POST 128M, Memory: 512M, Total max file upload: 128M
F1: 2edba60ed1f613d6dd804feb202456a2
Resource folder writeable: Yes
HTTP_HOST: newgateclocks.dev
DOCUMENT_ROOT: /Volumes/Data/g Websites/New Development/Newgate/CLOCKS FINAL 2
REQUEST_URI: /admin/core/settings/diagnostics/
SCRIPT_NAME: /admin/core/settings/diagnostics/index.php