Conditional field not working

Hi,

I would like to condition the display of a field (a list of modular templates) only if the page edited in the admin is a modular page. So I use :

        template_condition:
          type: conditional
          condition: "page.modular ? 'true' : 'false'"
          fields:

but it doesn't work.
At the opposite :

          condition: "page.modular != true"

works, and that's not normal, given that the page is a modular one...

Tests on the page's title also fail :

condition: "page.title == 'Recrutement'"
condition: "page.title == 'Recrutement' ? true : false"
condition: "page.title == 'Recrutement' ? 'true' : 'false'"

As

condition: "page.header.visible is same as(null) ? 'true' : 'false'"

seems to show the field, I deduce that the variables aren't set. There's a problem with the access to page's header in my blueprints.