[Orgmode] Uncover bullet points with BEAMER_env: ignoreheading

[Derek Thomas]

I've been using BEAMER_env: ignoreheading to generate columns of
bulleted lists as follows
#+begin_src org
* hidden heading 1                                    :BMCOL:B_ignoreheading:
  :PROPERTIES:
  :BEAMER_col: 0.5
  :BEAMER_env: ignoreheading
  :BEAMER_envargs: [<+->]
  :END:
** Item 1
** Item 2
* hidden heading 2                                    :BMCOL:B_ignoreheading:
  :PROPERTIES:
  :BEAMER_col: 0.5
  :BEAMER_env: ignoreheading
  :BEAMER_envargs: [<+->]
  :END:
** Item 3
** Item 4
#+begin_src org

But the "[<+->]" is not included in the LaTeX export so the bullets
are not revealed sequentially.  Is there a way to include this flag in
the export?  Thanks,

Derek Thomas