Custom formula function does not receive any parameters

[MaxDau]

Hi
I have built in a separate function for Formula. It is also called. But no matter what I enter, I don't get any values.

public function process(ArgumentList $args)
{
file_put_contents('data.json', json_encode([$this->getVariables(),$args]));
file_put_contents('entity.json',json_encode($this->getEntity()));
return false;
}​ 

The files are created, entity also has content, but data outputs empty arrays.
data.json

[{},{}] 

Complete Formula content is just one line.

my\function(true)

I have tested some other attributes. It always comes out the same.