org to beamer structure not working

[Luca Ferrari <fluca1978@gmail.com>]

Hi all,
I'm running emacs 26.3, and there's something I cannot reproduce in my
beamer presentation.
In my org file I've:

#+OPTIONS:   H:2 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
#+OPTIONS:   TeX:t LaTeX:t skip:nil d:nil todo:t pri:nil tags:not-in-toc
#+INFOJS_OPT: view:nil toc:nil ltoc:t mouse:underline buttons:0
path:https://orgmode.org/org-info.js
#+EXPORT_SELECT_TAGS: export
#+EXPORT_EXCLUDE_TAGS: noexport
#+HTML_LINK_UP:
#+HTML_LINK_HOME:

#+startup: beamer
#+LaTeX_CLASS: beamer
#+LaTeX_CLASS_OPTIONS: [bigger]

#+BEAMER_FRAME_LEVEL: 2



therefore I would like to have a frame for ever second level title.
My org file is:

* Intro
** Slide 1
Text 1
** Slide 2
Text 2


The result in latex is:

\section*{Intro}
\label{sec:org32f3cbe}
\subsection*{Slide 1}
\label{sec:org7e597e3}
Text 1
\subsection*{Slide 2}
\label{sec:orgb9aff87}
Text 2


that makes everything appearing on the same slide without a title and
a clear separation between frames. I've tried working with
BEAMER_FRAME_LEVEL but apparently no one value from 1 to 3 is working.
What am I missing?

Thanks,
Luca