You already appear to be on Screen1 ?
yes
A connection to the BTC should be established first. So, if BT enabled and BTC.IsConnected, BTC.ReceiveText...
What's up with your transparent backgrounds (PNGs)? I don't see any point in them. Besides, they crash the app (at least on the Google Pixel 7 Pro, Android 15 with Companion).
Apart from that, you have to request the Android version-dependent BT permissions. This issue has been discussed hundreds of times in the forum over the past few years and conclusively resolved, not least by me. → Bluetooth liste of devices deosn't work anymore - #7 by Anke
I got no problems with connection or sending/receiving data. My problem is when i click the notification it opens screen1 and then set the visibility of a VerticalArrangement (called "ScreenVerlauf") to true. But then it feels like the screen is static because the buttons dont work and there are no entries in the listview even there where entries beforehand.
but you are already on Screen1 ???
no i am on my home screen
tested it if i am already on screen1 and then click the notification the same happens.
There is only one screen (Screen1).
i meant the home screen of my phone
As I said, your app doesn't run with either the companion app or the APK (Android 9, 15). The app crashes or won't even start. Before we continue, first make sure your app can even start.
Well my app does start and i can use it. It seems to be crashing when i click on the notification.
Apparently Screen1 is reopened and reinitialized, so the ListView is empty again.
Device name & Android version?
I checked in on a Pixel and a Galaxy device → crash!
Samsung Galaxy S20 Ultra with Andorid 13
Same on Android 11 (Pixel 2XL)...
okay that is strange. On my phone it works just fine. Even with companion.
Then let your account name translate into action: "off to work" (nomen est omen). 
I now know how to fix my buttons. But there is still the problem if i click on the notification and screen1 opens and initialize all the data that was set beforehand is gone. I tried using the NotificationStyle extension because there screen1 dont initialize if i click on the notification. But i dont know how to use startValue in the "call NotificationStyle1.SimpleNotification" to trigger a procedure.
that extension is outdated and will not work anymore
you get that value in the get plain start text block, see also
Taifun
PS: do we now need 2 threads to discuss the same thing?