I have found a conflict with Gravity Forms and the WPML string translation plugin. When the WPML String Translation Plugin is activated the Form Editor no longer works. To be specific I can not add elements to the form editor. I can click on the options in the right hand column but none of them are added to the form. Using Chrome developer tools I get this error in the console:
Uncaught SyntaxError: Unexpected token < tw-sack.js:1
I will also be emailing the WPML team to see if there is anything they can do to help and I will let you know their response.
(I have tried enabling no-conflict mode in the GF settings and it does not help resolve the issue)