Answer
This is a UI-refresh issue rather than a sign the workflow didn't run — the page doesn't automatically re-pull the field's value just because a workflow updated it server-side, but performing an action that already triggers a UI refresh (like adding a new line to the record) causes the current, correct value to display; if a workflow-driven update needs to be visibly reflected without an extra unrelated action, consider whether the workflow can trigger client-side the same way an in-app edit naturally would, rather than relying on the page to notice the server-side change on its own.