On a brand new Drupal 7 / CiviCRM 5.6.0 install I created a custom field group for Grants and added one Contact Reference field and then created 2 grants. When I search for grants and export and try to export that Contact Reference field, the name of the Contact is limited to 16 characters.
Further testing indicates that the name of a Contact Reference field on a Contact record also is limited to 16 characters when exported.
ContactReference custom field saves contact id, and that field has max 16 numbers.
But when CiviCRM prepares Contact to export, that contact id(max 16 numbers)
transforms to contact's display name(more than 16 chars).
When CiviCRM tries to insert(to temporary table) more than 16 chars to field(with max length 16 chars)
then it slices that field.
This issue can be hot fixed in CiviCRM Core.
1. Find civicrm/CRM/Export/BAO/ExportProcessor.php file;
2. Find getSqlColumnDefinition method;
3. Replace varchar(16) to varchar(255).
CiviCRM Core need to add new condition: if is Custom Field with type ContactReference then use varchar(255) instead of varchar(16).
Here’s a PR that was closed and does not cleanly apply anymore but when applied manually I have a functional export for ESR 5.13.x
