org beamer strange behaviour

[Guillaume MULLER]

Hi,

I'm writing a lot of my courses in Org with a final export to Beamer/PDF.

Recently, I tried to improve the slides for a course I gave last year. When I 
opened the org file, I got a very weird coloring, as if a section was not 
closed correctly. You can find the org file and a screenshot of the rendering 
here:
https://seafile.emse.fr/d/f689a4318aff4e12a72e/

What's VERY strange to me is that whatever (sub)sections of the org original 
file I extract and yank/paste in another org file, then everything is OK...

Any idea what could be wrong?

--
Guillaume MULLER

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