When will scientists be able to work out how chameleons go invisible and implement it for humans?

Chameleons don't "go invisible" they have specific pigment producing cells in heir skin that produce the colors of red, gold, and green. These three colors mix and blend which allows the chameleon to blend into their surroundings. It's the same principle as three color printing and painting. Science does know what these cells are and how they work. They also understand the limitations of these cells and why a chameleon can't turn plaid or checkerboard. For  these cells to be in human skin it would require genetic manipulation and splicing of DNA in human egg and sperm cells and no ethical scientist would do this unless it offered a potential cure for a dangerous genetic disease. 

They have it figured out.  that lamp in your living room is actually an FBI agent.

Hi Aruke,

I don’t know but it’s a bloody good question!

I’ve been quietly testing a lot of genetic modification on my spouse whilst she is asleep but, as of yet, the only result I’ve seen is her getting angrier and angrier, may have a potential Hulk style situation!

I’ll keep you updated as I go along!

Chameleons do not go invisible. 

They “camouflage” but that’s also kind of wrong. They change color based on their emotions. So depending on how many emotions they express, they’re going to blend into the surrounding. There’s no reason for them to change skin color to camouflage since they already naturally have camouflage. 

There are already suits and cloaks that makes people invisible. It’s like the green screen that you see meteorologists use. If he wears something green, an image shows up where the green is. If there’s no projection then the green area becomes invisible. 

Chameleons don't "go invisible." They change colors. Ethical considerations prevent modifying human bodies to do this. 

Since chameleons do not go invisible or turn into trees or tartan, the question is pointless.

If you are asking why humans are not able to adjust their skin color to fit their environment, it is because it is an ability that would give little survival advantage to humans.