Just a note on-the-fly: best practice is to not hide/show components like buttons - imagine if that happened on your car dashboard - totally confusing!
SCREEN1, SCREEN2 and CONTROL are buttons and should be identified as such.
So, the data for the graph should be from the Arduino Nano? The Sketch LED_COBAK6a.ino does not send anything, it only receives.
I might add at this point that there is a recent beta update of the BLE Extension to work with Android 12:
I think your Clock1 timer Block is an attempt to receive data (x,y?) from the Nano?
The values should be sent together in sequence from the Nano, using one UUID Characteristic. A clock timer is not required for real-time streaming, the BLE extension has a block for that, you just have to register it first.
For example: (note, I'm not familiar with Juan's Extension)
