htop does not show all processes
Solution 1:
By default, htop hides kernel threads like nfsd. To show/hide kernel threads, press uppercase K to toggle. htop will save you settings when you exit.
https://askubuntu.com/questions/145707/why-doesnt-htop-display-the-same-processes-as-top
Solution 2:
Run htop under an administrative account like root, you can use su - to drop in a root shell to execute htop or you can instead run sudo htop if you have sudo installed.