Mobile Web test - "Unable to get screenshot from device" error

Hi all, 

I'm trying to develop my first Mobile Web test by using the Android Studio emulator and Appium. 

But I'm blocked now because, when I click on "Show Mobile Screen", I receive the following error: "Unable to get screenshot from device.".

I have not understand how I can check the FLAG_SECURE within the Emulator and disable it.

Can you please help me to understand how to solve this issue?

Below a screenshot of the error and the correctly running Android Studio emulator.

Thanks.

Simona