Yes I know this thread is a touch old but I have lost my chams alot while free ranging.
We once lost jasmine who was in her indoor free range but then walked down and walked straight through the door. It took us 3hrs to find her. there have been many more times also. But if anyone ends up losing it again then my reccomendation is too look at night because they are inn theyre sleepy colors.
Also we used to have free ranges interlocking with their cages and we'dleave them open and then go somewhere. We'd come back and find jasper on the cords. The scariest thing that happened was jasper escaped from his interlocking cage and walked across to jasmins cage. Luckily it was closed but jasmine ran to the bottom of the cage, black and mouth open, and she charged at him. They had a battle through the glass. That's why I stopped using the interlocking free range with multiple chameleons. Now thwy have separate trees far away from eachother and are never out of their cages without supervision. Learn from your mistakes but it can be too late because it's very easy for them to get permanently lost