Never heard of this.
See here.
Herodotus said:It has twelve covered courts six in a row facing north, six south the gates of the one range exactly fronting the gates of the other. Inside, the building is of two storeys and contains three thousand rooms, of which half are underground, and the other half directly above them. I was taken through the rooms in the upper storey, so what I shall say of them is from my own observation, but the underground ones I can speak of only from report, because the Egyptians in charge refused to let me see them, as they contain the tombs of the kings who built the labyrinth, and also the tombs of the sacred crocodiles. The upper rooms, on the contrary, I did actually see, and it is hard to believe that they are the work of men; the baffling and intricate passages from room to room and from court to court were an endless wonder to me, as we passed from a courtyard into rooms, from rooms into galleries, from galleries into more rooms and thence into yet more courtyards. The roof of every chamber, courtyard, and gallery is, like the walls, of stone. The walls are covered with carved figures, and each court is exquisitely built of white marble and surrounded by a colonnade.
I think the answer to daft's question is partly that the archaeological world is not convinced by the claims of the Mataha expedition, and partly that there is a vast amount of salt water beneath the surface of the site, making excavation a very difficult proposition.