docx file mime wrong type back getMimeType

Hello,
When I check mime type I got wrong type for docx.
Code:

PHP Code:

$path='test.docx';
$file = new \CodeIgniter\Files\File($path);
$type = $file->getMimeType();
echo $type; 


I got:
application/octet-stream
But if use file from bash:
 file -b --mime-type 'test1.docx'  I got:
application/vnd.openxmlformats-officedocument.wordprocessingml.document
Any idea what is problem?