You get the Helping Hand challenge by completing three challenges: The Foreman (make Vanya meet with the Laundry Foreman), The Artist (make Dawood pose for the painting so the artist can finish it) and The Kashmirian (make the Kashmirian meet with the Maelstrom).
I’m a bit confused by your description, but it sounds like you’ve either missed Vanya meeting with the Foreman or the Maelstrom meeting with the Kashmirian himself or both.