Nextcloud icon unseen at system tray

Having nextcloud-client installed, I started it.
However, the app icon, which is supposed to be seen at system tray (plasma), is not shown.
I ensure that the app is running at background. When typing ps -ef|grep nextcloud, there is 4325 4002 2 09:27 ? 00:00:22 /usr/bin/nextcloud shown.

So does anyone know how to settle this problem down?

Basic info about my os:

"uname -a":"Linux s2 5.15.57-2-MANJARO #1 SMP PREEMPT Mon Jul 25 01:32:51 UTC 2022 x86_64 GNU/Linux",
"pacman-mirrors --api -G":"stable",
"desktop":"plasma KDE"