Back button doesn't exit the app.

Expected behavior

On screen back button button in the app should exit the app when it says press again to exit.

Actual behavior

In app back button doesn't exit the app even after pressing after the pop up message press again to exit.

How to reproduce

Launch the app.
Open a folder.
Press the onscreen in app back button.
The app will say press again to exit.
Now try to exit the app by pressing the back button.
The app doesn't exit.

• App: Ultra explorer[Root browser] v1.2.9
• Operating system:Android Nought (7.0)
• Device: Motorola moto g5 plus

Recording Of The Bug