I do think she may have been mistaken. The Schiphol website still indicates that there are airside lockers in both Lounges 1 and 3, as well as those airside.
I'm not due to pass through the Schengen part of the airport within the next 6 weeks or so but perhaps someone else reading this thread, and who knows where they are, might like to check and post whether they are now somehow inoperative or removed.