Keys "Left", "Right", "Up" and "Down" don't work on xfce (xubuntu)

Hello. Recently I installed Xubuntu (with XFCE) and encountered a problem.
Namely, keys "left", "right", "up" and "down" on the numeric keys don't work on PHPStorm editor.
I mean, the separated arrow keys work, but I am used to using keys on the numeric part of the keyboard (in the right part).
I used to use Ubuntu with GNOME before, it was fixed with the Gnome Tweak Tool program, but it doesn't work with XFCE.
Also, I couldn't set these keys on PHPStorm settings, because it doesn't distinguish arrow keys and the same keys on the numeric keyboard.
Could you clarify me, how can I solve this problem?