My Shelly only turns on, not off.


https://user-images.githubusercontent.com/37381800/117358523-8dba2680-aeb6-11eb-945f-00f6347d5c0d.mov



**Describe the bug**
Hey, all my Shelly can only be switched on, but not switched off again. If I turn on the Shelly in HomeKit, then turn it off again in HomeKit, nothing happens. If I then turn the Shelly off via the web interface, then turn it on again via the web interface, it works.


**Log output**
This happens, when I press on the button in HomeKit, I pressed the button every time twice, to turn it off afterwards :/

```
[06/05/2021, 21:52:41] [Shelly] Setting relay0 of device SHSW-25 68C63AFA35C8 to true
[06/05/2021, 21:52:42] [Shelly] Setting relay0 of device SHSW-25 68C63AFA35C8 to true
[06/05/2021, 21:52:43] [Shelly] Setting relay0 of device SHSW-25 68C63AFA35C8 to true
[06/05/2021, 21:52:45] [Shelly] Setting relay0 of device SHSW-25 68C63AFA35C8 to true
```

**Environment:**
Shelly 2.5
v0.18.0
Raspberry Pi
