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A. Check that the user account in Salesforce that is being used for the sync is ticked as a Marketing User, so that they have access to Campaigns. If that is correct, check whether you have any validation rules or required fields on Accounts, Contacts or Campaigns that might block a record being created in Salesforce.
Q. How do I get help with the Humanitix Sync?
A. Check out the FAQs on the Humantix website https://www.humanitix.com/faqs