Thanks for responding: Here are the details based on a simple flow combined with a form.
Form
This captures the text input.
The flow processes the Form response to populate the plain text control on a docx template with the text from the form

The template docx has a plain text control named FormDataInput the result of the flow saves the updated document...
The control value has not been changed. The Word Online: Populate a Word Template connector has changed the placeholder text "Click or tap here to enter text" to the text I input into the form "Text for Word Document"

I expected the value of the plain text control to change - as would happen if a user inputs text to the control directly.
How can I update the value of the plain text control in the template rather than the placeholder text?