HI @alfred,
Sorry to hear of the problem you are having.
This can be due to plugin conflict on your site so please try temporary deactivating all plugins except Unyson plugin and WpBakery page builder plugins and see whether everything works fine and then enable the plugins one by one to see which plugin is conflicting if any.
Also, can you please try temporary enabling WP_DEBUG mode? To do this, just go to wp-config.php include this:
define('WP_DEBUG',true);
You might already have a line for WP_DEBUG, so just make sure it’s set to true.
Let me know what errors if any you are getting when you face this issue.
Best regards,
Shufflehound team