Hi there,
Actually, this is known issues on EasySocial v1.4.x . This issues only happen when you use Mozilla Firefox only.
This is temporary fixed for this issues. I have tried to acess your FTP but it seems that your given credentials is not working. Can you replace attached file to path below.
...\media\foundry\4.0\scripts\iframe-transport.js
Note: Currently, you have to run your site on "Development mode" as this javascript can't be compiled yet. Sorry for any inconvenience.
Please give it atry and see how it goes.