Missing data in $beforeUpdate callback function

Hello! 
I try to create a

Code:

$beforeUpdate

 callback function to change date format for database:

Code:

protected $beforeUpdate = ['changeDateFormat'];

And when i try to check the incoming data, then i see that many fields are missing:

Code:

public function changeDateFormat(array $data)
{
        dd($data['data']);
}

It has only three fields: [id, fk_loan_id, updated_at], but it should have many more fields, like: base_data, loan_balance etc. 
Why can't i see all the values and how can i fix it?

Thank you for any help!

All fields must be specified in the $allowedFields class property. And also if they are changed.

All fields must be specified in the $allowedFields class property. And also if they are changed.

I understand that, but i have these fields declared in allowedFields property:

PHP Code:

protected $allowedFields = [
        'foo', 
        'bar',
        'baz',  
        'id',
        'fk_loan_id',
        'another_field',
];