[Official Census docs (Salesforce destination)]: To clear a Salesforce field, sync NULL values from your source; Salesforce ignores empty strings and makes no changes. If a Salesforce sync is slow, check for automations, process builders, or Apex triggers on the objects being written, because Census uses the bulk API and must wait on those; pause automations on that object for full syncs. Multi-select picklists need strings separated by semicolons (Snowflake: LISTAGG with ';', BigQuery: ARRAY_TO_STRING with ';'). For lookup fields, the looked-up field must be exposed as unique and an external ID on the synced object. Press Refresh Fields one last time before saving a sync to pick up newly created fields.

Context: Official docs (Census/Activations Salesforce destination): documents three Salesforce sync gotchas that trip agents. Empty strings do not clear fields, only NULL does. Slow syncs are usually blocked by automations, process builders, or Apex triggers on the bulk API. Multi-picklist fields need semicolon-separated strings, and lookup fields require the external ID to be exposed.