@Monroe 

Go into your Alexa app, and head to the Smart Home menu, scroll all the way down, select "Your Smart Home Skills", wait for them to load, now tap "TP-Link Kasa". Disable the skill, then enable the skill, you will sign in with the same email and password you are using on the official Kasa app to relink the devices. They should now be discovered by Alexa.

@Tony that doesn't work, unfortunately. 

Disabled the skill, re-enabled. Logged in fine. 

Kasa and Alexa can control the devices directly just fine. Just no voice control, something went wrong... 

Seems the skill is the issue. 

@Monroe 

Does your Alexa voice control work for everything else?

I have exact same problem, has this been resolved?

So I was able to get this to work.  First if you are using the Alexa app on your phone or tablet to activate the TPLink skill it is not properly transporting.

I went to the alexa.amazon.com website on my PC and found that the skill was not there.  I added the skill on the pc website and surprise the light started working.

So,this seems like a coding problem having to do wth the transport of the skill out of the phone app to the actual cloud app.  I would have hoped this would have surfaced during testing but apparently it did not.  I hope this information allows a developer or quality engineer to get this fixed.

This is one of the major griefs with smart devices and external controls, too many bugs and the suggestion is always that the user is doing something wrong or the user's other hardware is not working properly. 

This is pretty sad.

@HighCommand I've tried everything you suggested - Alexa still not recognizing.  

@Ruthie53 I am not having any issues.  You need to add the skill on a pc through the amazon management page.

The problem I found on my setup was that the cellphone app was not transporting the skill to the amazon servers.

If you have done that you might try deleting the app and the skill and setting up the devices again.

This solved my isssue, I don't have any other suggestions.