In the official documentation, the ‘variable definer’ topic is never meant to be invoked. It is primarily there to define the your custom variable names for the Copilot Studio authoring experience. E.g. the topic is there so you can directly reference the variables later as you're writing your topic flows. You'd never want to actually invoke the ‘variable definer’ topic directly: it would override the variable values to blank/empty text.
From what I can see in your screenshot, you're invoking a topic that reads out the variables correctly (name, email, and phone came back fine), but then you're setting the values to empty right after it.
Try moving the variable defining nodes into a separate, un-called, topic.
