in file CFDBViewShortCodeBuilder.php line 1825 presents a little typo that breaks javascript execution if wp debug is enabled
jQuery('#header_cntl').prop("checked", <?php echo $this->requestParams['$postedHeader'] == 'false' ? 'false' : 'true' ?>); // default = true
this line cause a undefined index error '$postedHeader' is not defined
change it like this
jQuery('#header_cntl').prop("checked", <?php echo $this->requestParams['postedHeader'] == 'false' ? 'false' : 'true' ?>); // default = true
https://wordpress.org/plugins/contact-form-7-multi-step-module/