@JustinAtSense , it may just be a matter of phrasing, but… to my memory from when Smart Plugs were first introduced, Sense actually actively tried NOT to detect devices that are behind a smart plug. That isn’t to say that it was impossible, but I feel like the few people I remember getting device detections from behind a smart plug, it ended up just that an old data set was finally processed and the device model pushed out.
I did find this old post from Ryan, but of course things could have changed.
@matthew_lasorsa, if Sense is looking at on/off transients as its main method of detecting a device, I would expect that using a devices built in power switch vs the Kasa plug relay could appear differently to Sense depending on the switching mechanism. I think @andy’s comment about a change in waveform makes sense. Depending on the kind of solenoid / solid state relay or whatever the switch is will make the start up ever so slightly different. Its why it is recommended to not go turning on/off breakers to try to make a bubble appear/disappear when trying to track down a new unknown device. The action of flipping a break may introduce or cut power to the device in a different manner than what the device usually does, therefore not looking like what Sense expects.