block folding - should this work?

[Robert Nikander]

I started reading about “blocks" in the manual. I wanted a chunk of text that I 
could hide, so I tried this:

* Test
Some text
#+BEGIN 
Hide this
#+END

Hitting TAB on the BEGIN line does nothing. But if I add a blank line before 
it, then hitting TAB hides and shows the block. Is that a bug? Or am I doing it 
wrong? Seems like it should work without the blank line.

* Test
Some text

#+BEGIN 
Hide this
#+END

M-x org-version => 9.5.1.