Taxonomy term label not working in REST Export Views via postman or reqbin

I've setup a views in REST Export Views with this config:

Format = Serializer => json
Show = Fields
Fields = field label from taxonomy term (select list)
Access = Unrestricted

in Preview or accessing it via browser i can see the taxonomy term label (its looks like setup correctly)

[{
   "name":"196803212007011004",
   "field_nama":"ASANI",
   "field_eselon":"Non Eselon",
   "field_jabatan":"Guru Muda",
   "field_jenis_jabatan":"jft",
   "field_pangkat":"III/b",
   "field_perangkat_daerah":"Dinas Pendidikan",
   "field_unit_kerja":"SMK Negeri 5 Sungai Penuh"
}]

but when test in postman or reqbin the data label not showing, this is the results:

[{
    "name": "196803212007011004",
    "field_nama": "ASANI",
    "field_eselon": "",
    "field_jabatan": "",
    "field_jenis_jabatan": "",
    "field_pangkat": "",
    "field_perangkat_daerah": "",
    "field_unit_kerja": ""
}]

as you can see the value from label formatter of the field with taxonomy term (select list) is empty.

I've examined the configuration but i do not understand what going wrong, i hope anyone else experienced this and show how to solved it.

Would anyone know and help how I can retrieve the value in label formatter of taxonomy term, not the raw output.

Thanks in advance.