What’s the scuttlebutt on why non-invasive technologies weren’t approved for analysis? Do you suppose they weren’t adequately understood...or were those using them deemed untrustworthy (i.e. that they might surreptitiously use an invasive technique as part of the analysis)?
In the 1980s a French team used I forget what to look for unknown chambers and whatnot. Their detector found a probable void right near the entrance to the King’s Chamber, on the left as one is going up. The blocks there don’t overlap (as bricklaying as well as stone masonry is generally laid) and it looks for all the world like they were slid in to fill the previous opening. The Gyppoes gave permission for a test hole. The stone was drilled through, and a sand-filled chamber of some sort was found. It wasn’t opened though. Never will be, probably.
The same detector spotted Houdin’s internal spiral ramp as well, but didn’t put it in their publications because it didn’t make sense at the time.