How to get multi-select custom fields from Get ticket API

Multi-select values should be returned in each ticket's custom_fields array as an array of option tag values, for example:

{"id": 21938362, "value": ["hd_3000", "hd_5555"]}

The Incremental Ticket Export does not return the display labels for those selections. I would isolate the issue with one affected ticket:

1. Request GET /api/v2/tickets/{ticket_id}.json and find the same custom field ID.
2. Request GET /api/v2/ticket_fields/{field_id}.json and confirm that its type is multiselect.
3. Map the ticket's value array to custom_field_options[].value. The human-readable labels are in custom_field_options[].name.

If the single-ticket endpoint also returns null, the value is not currently stored on that ticket. Check that you have the correct field ID and ticket form, and whether any field options were removed or changed. Zendesk notes that removing an option also removes that option's values from tickets. If the single-ticket endpoint returns an array but the incremental export returns null for the exact same ticket and field ID, that is a useful reproducible case to send to Zendesk Support.

For the initial incremental request, also include start_time, then follow after_url/after_cursor until end_of_stream is true.

Official references:
https://developer.zendesk.com/documentation/ticketing/managing-tickets/creating-and-updating-tickets/#setting-custom-field-values
https://developer.zendesk.com/api-reference/ticketing/ticket-management/incremental_exports/