It’s probably not supported as device. Tuya tends to change things over time, so some contact sensors are supported as device, others aren’t.
But that is no showstopper, you can still use it, as I wrote many many many times already:
Just read the 1st post of this topic again, and look for the ‘RAW commands’ howto.
RAW is Tuya’s version of MQTT.
In theory you can use any Tuya device with this app this way.
i saw that post, but ill read it over again.
i thought that i couldnt do it whit the sensor caus its not on off it should say in homey open or closed.
ill come back to you 
ref existing guides. There are no descriptions of API reference to use. Can anyone point me to a step by step guide to get up and running with Tuya WiFi devices on Homey.
Did you read the first post of this topic for instructions?
Hello,
i was using this app quite a while and it was running well, but some days ago, it just stopped working without any changes by me. Even i do not get an error. I can turn on and off the device in Homey, but nothing happens. When i login to tuya cloud, the device is working fine and “online” and from tuya app i can switch on and off the device. I restarted the app in homey several times, deinstalled and reinstalled the app, but nothing changed. If i would like to add a new device i always get the notice, i have to configure the app, but i did all of this. What i’m wondering about is, that i cannot test the conection. I have added all the credentials and secrets, but theres is no way to test the conection. Any idea or suggestions by someone?
Same here. I changed nothing, but every Tuya device stopped responding. When using the also installed Smartlife app everyting is working fine. Even with Google every device is still working
On the developers page of Tuya also no changes noticeable.
Something changed in the Tuya app config on de HP23?
Given that the app hasn’t been updated for months, a more likely cause would be that something changed at the TuYa end. Home Assistant’s TuYa integration has been rewritten recently because TuYa is offering a different method of authentication, perhaps that’s related.
So as this app has been stopped maintaining by the developer most likely i cannot use the Tuya devices any more, right? Or is there any alternativ way to connect them to homey?
That’s not at all what I’m saying, perhaps there’s just an issue on the TuYa side that needs fixing. Just wait.
so i cant figure out how to use the functions.
i have send a mesage whit the product id and value pir.
But the logic values are not yet there.
Do i need to make a new variable whit that name, or did i do anything wrong whit configuration?
You need to discover what those values are. Use the Tuya Cloud ‘when’ cards: ‘Boolean event received’, ‘Number event received’ and ‘Text event received’. Chances are your device is sending a boolean event so start with that. Add the When card in an advanced flow and use it to send the ‘Product id’ and value tags to your timeline. Activate your device - both on and off - and see what values you get in the timeline.
You can also get some information from the Homey developer tools, but, when I tried using it, the values I had to send were not shown by the tool (similar, but not the same).
Andy
If you connect your boolean When card to a Then card, you will be able to use the tags provided by the When card.
This is not a good place for a tutorial on flows, however. There’s a good starter video here:
I’m sure there are plenty of others in different languages.
Andy
Check if your IoT Cloud project trial hasn’t expired. If so, extend it.
so just conect the to and make hello world to a tag i chose?
the rest i`m kind of formiliar i just dont know how that is going to give me the text.
like i thought i miss somthing…
Here’s a screenvid:
.
Push messages after I turned some Tuya lights on/off:
.
Hint / advice: I think you should read / watch some info about flow creation. Go to support.homey.app and search for “flow”.
Now read all related knowledge base articles, and play with building some basic flows
Link:
https://support.homey.app/hc/en-us/search?utf8=✓&query=Flows&commit=Search
You’ll see there’s much much more info in there 
I have created the flow that I pointed out. Still after I control some of my Tuya stuff, it doesn’t send any push messages
Then something seems to be in error… Does “execute a scene” (which was made in the phone app) still work?
Or, your push messages are rate limited, this is only to discover when you test run the flow. The push card will then return an error.
To be sure it’s not the trigger, just add an other notification card, like Simple Log
