Can't edit info box module content

Hello the plugin author,

I can’t edit the info box module content. Web browser’s console shows JS error:

builder.main.min.js?ver=1.0.8.4:4 Uncaught TypeError: Cannot read property 'setContent' of null

Please see this screenshot https://cloudup.com/cXBRHJoyqRX.

The active theme is West (the latest version).

Active plugins:

* Maintenance
* Live Composer
* Simple CSS
* Wordfence Security

All of them are the latest ones.

I am running the latest version of WordPress as well.

Please help.

https://ww.wp.xz.cn/plugins/live-composer-page-builder/