Okay it’s working !
It was indeed a PHP memory limit that caused Visual Composer to bug.
As Kento suggested, I increased ‘WP_MEMORY_LIMIT’ from 64M to 256M and now VC is working just fine, no more infinite loading or JS errors.
Thanks a lot Kento !
Thanks for the answer. Here are the errors I get :
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send @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:5
m.extend.ajax @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:5
vc.EditElementPanelView.vc.PanelView.extend.render @ panels.js?ver=4.7.2:699
vc.shortcode_view.Backbone.View.extend.editElement @ composer-view.js?ver=4.7.2:347
m.event.dispatch @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:4
r.handle @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,jquery-ui-core,jquery-ui-widget,jquery…:4
——–
I defined WP memory limit to 96M but unfortunately it doesn’t change anything.