@outermagnolian,

Unfortunately, there is not too much debugging you can do for IFTTT. I would recommend logging out of your TP-Link ID from within IFTTT and then relogging in. It sounds like the platforms are simply not communicating with each other, whether it be from a bug, or from an authentication error. 

Have you used IFTTT with Kasa Devices before/ Are your other Kasa Devices controllable by IFTTT?

For your information, IFTTT is one of the older integrations for Kasa. I personally recommend looking at creating these types of automation in the app of one of our smart home partners, such as Apple Homekit, Alexa, Google Home, or the automation powerhouse that is SmartThings. These connections are officially supported and developed by our teams, so you may see better efficiency or stability in your automations