Customize gives a blank page

Hello,

I can no longer customize the homepage of your template. I get a white page without any error message. I tried to switch to other basic wp templates and I do not have this blank page with other templates, I can modifiy the homepage. I have been looking for a suitable solution in different forums and tried them all without success (adding lines to wp-config.php or wp-functions.php, extend PHP memory limit etc..)
Any help would be most welcome as this template is really great!
Thank you so much.

The page I need help with: [log in to see the link]