Why is this black box appearing on emulator?


I am a very new Ionic user; also a very new mobile developer. I have been making an application that uses tabs.

Everything looks ok on browser, but when I run application on emulator, this occurs:

This black box appears on every tab.

Why is this happening?

Is it a bug? How can I inspect the cordova browser on emulator as we do on firefox or chrome?

Thanks in advance.