When a field references a choice type, the "value" is being searched and not the "label".
1. Create a reference field for incident on sys_user.
2. Give the reference field these attributes: ref_auto_completer=AJAXTableCompleter,ref_ac_columns=subcategory,ref_ac_columns_search=true
3. Go to the 'subcategory' column for the incident table. Add a choice where 'Label' is 'Label' and 'Value' is 'Value'.
4. Create an incident record with the newly created subcategory.
5. On sys_user, in the reference field type 'Label'. No results are shown.
6. In the reference field, type 'Value'. Results are shown.
This is expected behaviour in the current design.