Custom validation rules not called when input data is a multi-dimensional array

Hello, when using custom validation rules defined in MY_Form_validation on input fields with multi dimensional array data, the validation function is not called at all in my tests.

I am sending the multidimensional array data using an ajax request with jQuery, the data is submitted alright, but it is just not validated.

Any help solving this will be greatly appreciated.

Regards,
Gaston