Strange behaviour of class casting

Z_STRANGE_BEHAVIOUR_OF_CAST.abap

REPORT ztest_class_ref_data.

CLASS lcl_abstract_data DEFINITION ABSTRACT.ENDCLASS.
CLASS lcl_abstract_processor DEFINITION ABSTRACT.
  PUBLIC SECTION.
    METHODS constructor IMPORTING io_data TYPE REF TO lcl_abstract_data.
  PROTECTED SECTION.
    DATA mo_data TYPE REF TO lcl_abstract_data.
ENDCLASS.

CLASS lcl_abstract_processor IMPLEMENTATION.
  METHOD constructor.
    mo_data = io_data.
  ENDMETHOD.
ENDCLASS.


CLASS lcl_data DEFINITION INHERITING FROM lcl_abstract_data.
  PUBLIC SECTION.
    TYPES tt_data TYPE STANDARD TABLE OF i WITH EMPTY KEY.
    DATA mt_data TYPE tt_data.

    CLASS-METHODS cast
      IMPORTING io_data        TYPE REF TO lcl_abstract_data
      RETURNING VALUE(ro_data) TYPE REF TO lcl_data.
    METHODS print .
ENDCLASS.

CLASS lcl_data IMPLEMENTATION.
  METHOD cast.
    ro_data ?= io_data.
  ENDMETHOD.
  METHOD print.
    LOOP AT mt_data INTO DATA(lv_value).
      WRITE lv_value. NEW-LINE.
    ENDLOOP.
    ULINE.
  ENDMETHOD.
ENDCLASS.

CLASS lcl_processor DEFINITION INHERITING FROM lcl_abstract_processor.
  PUBLIC SECTION.
    METHODS process .
    METHODS process2.
    METHODS process3.
ENDCLASS.

CLASS lcl_processor IMPLEMENTATION.
  METHOD process.
    DATA(lo_data) = lcl_data=>cast( mo_data ).
    LOOP AT lo_data->mt_data ASSIGNING FIELD-SYMBOL(<v_value>).
      ADD 1 TO <v_value>.
    ENDLOOP.
  ENDMETHOD.

  METHOD process2.
    LOOP AT CAST lcl_data( mo_data )->mt_data ASSIGNING FIELD-SYMBOL(<v_value>).
      ADD 1 TO <v_value>.
    ENDLOOP.
  ENDMETHOD.

  METHOD process3.
    LOOP AT lcl_data=>cast( mo_data )->mt_data ASSIGNING FIELD-SYMBOL(<v_value>).
      ADD 1 TO <v_value>.
    ENDLOOP.
  ENDMETHOD.
ENDCLASS.



START-OF-SELECTION.
  DATA(lo_data) = NEW lcl_data( ).
  lo_data->mt_data = VALUE #( ( 1 ) ( 2 ) ).
  DATA(lo_processor) = NEW lcl_processor( lo_data ).

  lo_data->print( ).

  lo_processor->process( ).
  lo_data->print( ).

  lo_processor->process2( ).
  lo_data->print( ).

  lo_processor->process3( ).
  lo_data->print( ).