It’s a rift area why wouldn’t there be voids?
The voids are within the built structure of the pyramid. There is a tunnel built that exactly replicates the entrance tunnel into the pyramid. There is a missing shaft that tilts up and back in the model. In the pyramid that shaft would go to one of the voids. The research team used Lazer mapping to compare the model with the pyramid.
Here is an article about the replica of the pyramid tunnel. Using Lazer mapping it was an exact match except for an ascending tunnel. This article does contain what I think are nonsense. http://thehereticmagazine.com/the-trial-passages-a-message-in-stone/