ESP32 does not connect to bluetooth

Hello everyone, i'm new to this environment.
I've followed several guides to send data to an ESP32 via BLE using the app developed via MIT App inventor.
Using the notification i've seen that the code runs until i choose a device to connect, but when i click on it it never connects.
What can be the issue?

Dear @Emanuele_Paolasini, welcome on board!
Before asking you to post also the .ino file, let me tell one comment:
whether you don't need the BLE for some specific reason, I strongly suggest you to start with the "classic" BT. The ESP is capable of both modes, and the classic is, by far, much simpler to use.
Another hint is to split the problem: as a first step try to connect your ESP to the Android device (phone or tablet, whichever you use) by means of a ready made tool such as Serial Bluetooth Terminal (free on google playstore). If it works, you can be confident that the ESP is transmitting correctly. Therefore, once you are done with this first step you can focus your attention to your app.
On the opposite, if the Serial Bluetoot Terminal cannot communicate with the ESP, this means that the problem is on the ESP side.
Best wishes.