And note that this problem is not related to a single HS220 dimmer. I have 4 installed and it's happening for all of them. And there has been some change that caused this problem as it previously worked normally.

  @Solla-topee I tried toggling the feature as you suggested (it was previously off) and it makes no difference. By the way, the feature is called "Ramp Brightness" in my Alexa app - probably a language translation difference. Note that the ability to set a brightness did previously work and I have a number of routines set up that used it. The problem just started occurring recently without any changes being made to the Alexa routines or to the Kasa device settings.

Here are screenshots of all the relevant settings.

Simple Alexa routine for testing. Just turns the light on and sets to 25%.

Here's the detail of the device settings. Note that with these settings nothing happens for the device. It won't turn on or react at all. If the option to set the brightness is disabled then the light will turn on (at previous brightness) under the routine's control.

Here are the settings for the HS220 device in the Kasa app:

  @Solla-topee Some further info:

I found that if I leave the "Increase Brightness" (or "Ramp Brightness") feature enabled then the light will turn on instantly to the previous brightness. This is regardless of the amount of time to increase the brightness. If the "Increase Brightness" option is disabled then it's as before - no response from the light.

So to recap, if the routine:

Only turns light on/off - works but sets the brightness to whatever the light was set to previously.

Turn on and Set brightness (with increase brightness off) - no response from light

Turn on and Set brightness (with increase brightness ON) - light instantly turns on to previouse brightness and doesn't ramp and doesn't use the brightness setting in the routine.

  @Solla-topee 

I discovered another thing related to the problem. It's no longer possible to set the HS220 dimmer brightness using the Alexa app. Manually controlling the HS220 with the Alexa app allows you to turn it on and off, but if you try and change the brightness by moving the slider the message "There was a problem" briefly appears at the top of the page and the brightness doesn't change. So it's easy to replicate this problem. Simply bring up the device in the Alexa app and try to adjust the brightness.

Note that using voice commands via Alexa devices (like an Echo Dot) works correctly and the brightness can be set on the HS220.

So the failure use cases are:

1. Can't control brightness via a Alexa routine.

2. Can control brightness using the Alexa app.

The HS220 seems to work normally using the Kasa app.

  @Solla-topee 

Here is the message that appears in the Alexa app when trying to adjust the brightness of a HS220 dimmer. Note the "There was a problem" message highlighted by the yellow box. The message appears for just a couple seconds whenever you move the brightness slider. And of course the brightness control doesn't work. The HS220 can be turned on/off, but dimmer level can't be adjusted. To replicate simply try to adjust the brightness of a HS220 using the Alexa app (not via voice commands). So this along with the problem controlling from routines indicates there's some integration problem between the Kasa device/service and Alexa.