Use classes from external libs

hi
i managed to include an external library,in onscriptinit in control application, however when i call a class
the sc controlapplication page stops working .

(in plain php it all works).

use PhpOffice\PhpSpreadsheet\IOFactory;

this is code on init

sc_include_library(“prj”, “import_files”, “vendor/autoload.php”, true, true);
use PhpOffice\PhpSpreadsheet\IOFactory;

it does not work in blank application too.

so no one here ever loaded external libraries via autoload.php?
why it is not working?

is this a bug or intended?