I'm using Ubuntu 20.04 LTS, installed XFCE4 version 4.14.3. My computer is Casper Nirvana Model: C810. I have a problem with FN key. When I push to FN+F12 (increase volume) or FN+F11 (Decrease volume) one time then it is keeping continuosly by the Xfce. When this occurs I can't able to use keyboard anymore. I must hard restart the computer as long press to power button. When this problem occurs I can't open a menu (for example right click to desktop but menu not opening), keyboard not responsible etc. This problem not only for sound. Every shortcut occurs this problem (for example increase/decrease the backlight).
In Gnome everything is working correctly. This isn't hardware problem. I'm facing this problem only Xfce.
I searched this error in google (https://www.google.com.tr/search?q=xfce%20keyboard%20fn%20key%20continuously) but I didn't find any solution. For this I'm asking here.
Do you have any idea for solve this? Thanks.