Weird behavior of Unity hub's Getting Started

The Unity Hub's Learn > Getting Started > 01: Play & Edit Mode has a problem that the character control with arrow key does not work appropriately.

When I hit an arrow key once, the character infinitely moves the corresponding direction. Any further key control works a little bit but it's not enough to change the moving direction. As soon as the character hits against a wall, the focus window is switched to the Scene view. Clicking the Game view refocuses the Game view so that I can restart the game with Esc key. Funny thing is that A, S, D, W keys work appropriately.

My environment is as follows:
- Unity Hub: 1.6.0
- Unity: 2018.3.10f1 (f88de2c96e63) Personal
- OS: Linux (Ubuntu 16.04.6 LTS)