Thank you. I found that skip-empty-rows works correctly only if ITEM is in the COLUMNS property. Here is an ECM :).

As you can see, when ITEM is not included in COLUMNS property, it generates an empty line for the parent heading.

* Columnview with ITEM in columns

:PROPERTIES:

:COLUMNS: %ITEM %Variable

:END:

- This correctly skips the parent headline because ITEM is one of the columns

#+BEGIN: columnview :hlines 1 :id local :maxlevel 2 :skip-empty-rows t

| ITEM | Variable |

|-----------------+----------|

| ** Subheading 1 | 1 |

| ** Subheading 2 | 2 |

#+END

** Subheading 1

:PROPERTIES:

:Name: Subheading 1

:Variable: 1

:END:

** Subheading 2

:PROPERTIES:

:Name: Subheading 2

:Variable: 2

:END:

* Columnview without ITEM in columns

:PROPERTIES:

:COLUMNS: %Name %Variable

:END:

- When ITEM is not in columns, columnview generates one empty line on the top:

#+BEGIN: columnview :hlines 1 :id local :maxlevel 2 :skip-empty-rows t

| Name | Variable |

|--------------+----------|

| | |

| Subheading 1 | 1 |

| Subheading 2 | 2 |

#+END

** Subheading 1

:PROPERTIES:

:Name: Subheading 1

:Variable: 1

:END:

** Subheading 2

:PROPERTIES:

:Name: Subheading 2

:Variable: 2

:END: