Cache Settings
There are many approaches, and multiple solutions, to site caching, including various WordPress plugins. When the site cache lifetime is too high, the forms may not be submitted. We recommend decreasing the site cache lifetime to optimize performance while preserving security. Setting a site cache lifetime of around 48 hours should be sufficient to avoid submission errors.
When Caching plugins are installed and JavaScript Minification, JavaScript Combination, and Script delay options are enabled, it is required to exclude the page where Calculator is added from these services.