Check whether there is installed latest version of plugin. At this moment it is 2.2.0-2.4.0. You can get latest version at your account or marketplace where you purchased plugin.
Also there might happen a conflict with other plugin or theme. So you can try to disable plugins one by one and test Visual Builder to find the conflict plugin. If it does not work when all plugins are disabled (except Content Editor). You can try to activate another theme.