How do I troubleshoot issue with field mappings?

Mapping fields is possible in several places in the integration. Below are notes to help you troubleshoot the most common mistakes.

• All mappings must match in data type. For example, Salesforce picklists can map to Mailchimp single-select lists or text fields. Please refer to the FAQs for checkboxes and multi-select picklists. 
• We recommend creating new merge fields from the app, with the New Merge Field button above each mapping. We will handle the data type match for you.
• Be sure to consider these common fields, which may require special handling: phone numbers, addresses, full names and birthdays.

Data Wizard (guide)

• The Salesforce fields for mapping must be available on the wizard's source. They should be columns in the list view or report, campaign member fields, or SELECT parameters in your SOQL query.
  
  Example - To map a contact's First and Last Name instead of Full Name, you should include First and Last Name fields as columns in your report or list view.
• All Salesforce fields must be available to the running user via field-level security. This is already true if you are the running user and can include them in a report/list.
• You can preview the data before importing, on the last screen of the wizard. Click the Preview tab.

Field Mapping (guide)

Always check Maintenance log for errors in field mappings. (Maintenance logs & email alerts)

Mailchimp to Salesforce:

• All Salesforce fields must be available via field-level security to the Salesforce Sync user. (User Security)
• If you are creating records, the data can't break Salesforce validation rules or field requirements.
• You can preview mapping rules. 

Salesforce to Mailchimp: 

• Users should have our limited permission set so their record edits trigger mappings. (User Security)
• Merge fields that are required on Maichimp forms can break the update if not populated (by field mapping or already filled in Mailchimp when we attempt to update Mailchimp).