It is not a bug, you simply need to use a dataset on your page to save your user inputs from your form. Without a dataset, you are not going to get any values sent in your triggered email.
See here about creating a user input form.
https://support.wix.com/en/article/creating-a-form-with-user-input-elements
Hence why I said in previous posts that you need to use onAfterSave.