Since mainstream launch of Wayland with Gnome, people are facing problem in using xclip. Mainly because xclip is supposed to work with X11 Clipboard.
But fortunately there is an option in xclip to overcome this propblem. Just use xclip -selection c instead of xclip. This option will just emulate the ctrl + shift + c action.
For easier use you can setup the alias by adding following line in .bashrc or .zshrx file.
alias xclip='xclip -selection c'