Hi mok ,
Thanks for the screenshot!
From what I understand, it only crashes whenever you try to go to the styling tab in the button settings.
If this is correct, it sounds like your site may have PHP 5 or lower.
Since Buttonizer version 2.1, we have optimized our code using PHP 7 features, making no longer compatible with PHP 5.
We recommend upgrading to PHP 7 since it is much faster and safer than PHP 5.
You can read more about this in our knowledge base topic here:
PHP version is outdated.
Let us know if this was the case for you! 🙂