FYI, here is info from Zapier on why it doesn’t work:
"Right now, we’re running into a limitation with the Asana API. Projects are being paginated to only return 50 at a time so there’s not much we can do from the Editor standpoint, but make that call over and over to return a new set of 50.
So, to answer your question, right now this one is not currently possible but our team will be on the pulse of any updates to the Asana API to open up the pagination limits. "
In other words, if you have more than 50 projects, this will not work.