@jlboggsCO I am having the exact same problem and I see some people complaining about it on the Alexa app review forum. It's driving me crazy. I've tried to unlink and relink the Kasa skill in Alexa with no result.

  @Msmillefiore I did some troubleshooting last night and noticed that the same devices are unavailable in the Kasa all if I disconnect from my local WiFi. This lead me to believe this has something to do with allowing remote access to switches. For some reason, they removed the remote access toggle from their app. I was able to fix this by resetting each device. It's a huge pain, but luckily when you reset and re-add a device, it retains all of its settings. When adding it, make sure you select "Do not reset". 

  @Msmillefiore it varies from device to device. For plugs with a single button, you hold it down for 5ish seconds until I flashes blue and orange. Wall switches have a reset button that you hold for 5 seconds.  Bulbs are power cycled 5-8 times, depending on the model and hardware version. 
 

I recommend disconnecting from your wifi and refresh the Kasa app to figure out exactly which devices need to be reset. It's possible that not all need to be reset. I believe I had to reset 8 devices, which is about half. You'll need to re-join your wifi to add the devices. 

  @jlboggsCO I'm also having this issue, realized outside light were still on while leaving this morning but I could access them and 5 other devices through Kasa. Later while on our wifi I could control everything but all 6 devices were unresponsive on Alexa. Does anyone know if this is a Kasa issue or an Alexa issue? 

  @Solla-topee your solution tips did not work. I have unlinked and re-linked the Kasa skill with Alexa multiple times, and re-discovered the devices. It will recognize the devices, but when I try to use them with Alexa I get the message "device is not responding."  

I can control the devices using the Kasa app while on local Wi-Fi, but nothing works while using the cell phone network. 
 

The only device that works is the one that I completely removed from kasa and set up again like was recommended above. I do not have the time to deal with this, and I have not set up the other devices again. 
I don't want to provide the information you asked for on a public forum. Let us know if there's an alternative way to provide it- this is definitely an inconvenience. 

  @Solla-topee i don't know how to get the MAC address of a device and I don't know how to date and time stamp the error message. Maybe someone else can do this for you.