None of the methods seems to work

[matejdro]

I have tried all the methods and all of them seems to do exactly nothing. I get popup that Taskkill has been granted superuser, but that is about it.

Phone:
OnePlus 3
Resurrection Remix ROM (based on Android 7.1.2, August 2017 security patches)
Magisk root (I assume Magisk incompatibility could be a problem?)

[matejdro]

Also note that simple am force-stop <package name> action in "Run Shell + Use Root" Tasker action works. This is supposedly equivalent to "Extreme" option.