Hi Nicolas,
Always Chrome
All other pages like this one work fine, when I place the 'Fly' (or 'Form') brick on the page the border turns green, then goes through its loading process, but the fly brick does not appear.
Also when I click on the folder to work on the page, it opens a tab (like normal), but if I click again it opens another tab, and if I keep clicking on the folder it keeps opening a new tabs that sometimes you can click on and sometimes you can't, very strange.
I do believe this is a builder issue as I did try Firefox as well and the exact same problem occurs.