Strange issue when scaling text

Hi,

I'm using inDesign CS6 and there's a strange issue when rescaling a text with overflow to 200%:

As you can see, the fourth paragraph doesn't change its font size, even if it has exactly the same configuration. This happens apparently randomly to some paragraphs, or even lines of a paragraph in some cases.

The weirdest thing is that I have tried the same action with the same .indd file in other computers (another Mac and a Windows one, both CS6) and it scales properly all paragraphs. So I checked all the preferences from one computer to the other, and even if they are the same, the scaling issue still happens.

Any hints?