App studio - Workflows setup: search_term not working

According to the documentation here
search_term can be used on dropdowns to automatically add the parameter on !http requests.

I’ve tested it multiple times with various configurations (even with the provided example) and the search_term parameter is never sent to my API. Are you sure this is working?

Just to provide some context: My use case is to provide some sort of validation to a text field. i.e: a field that cannot use unicode characters, my API endpoint automatically normalizes the searched value into a proper one and returns an array of valid options that can be selected.

When comparing this to other self-service app platforms like Make or Zapier, the form_fields section seems very limiting.