I have a theory that you may be running into a conflict with how Formidable displays multi-page forms. When you hit next and previous in a multi-page form, Formidable converts all fields that are not displayed on the resulting page to hidden fields. You can confirm this by examining the form's source code in your browser's inspection tool. Fields that are supposed to be shown on a specific page are converted from hidden to their original defined type. It's hard to say the exact cause of the issue you are experiencing without further debugging in your system, but it's possible your code is actually working and Formidable is resetting it when the page displays. To test what's happening in your system, I would use a PHP debugger like Kint or Xdebug that allows you to set a break point so that you can pause code execution when the filter is invoked to examine the when and how the field type is changing. If your code is working, you'll see the field's type change. If it changes as you expect, but if the toggle is still a radio button on the form, then Formidable changed it back because of the multi-page functionality. It's unusual that you are using this filter to change a field type. Normally, hiding showing fields is handled through conditional statements or jQuery .hide() and .show().