Empty session in RESPONSIVE filemanager?

Question

Yii

In Yii2 form, TinyMce added a RESPONSIVE filemanager to the dosamigos widget. Everything is working locally on openserver under Apache. But on the network on the server under Nginx, uploading files in the editor does not work.
I found out that the problem is with the post request /plugins/responsivefilemanager/filemanager/upload.php . This file contains an empty session $_SESSION['RF']["verify"]. Although before that, the dialog.php file is loaded and its value is declared there.
The session is created in the upload.php file, I checked it.
I don't understand what's wrong?