SystemUI not in list of apps to kill

If you click the cross-arrow button in the action it should switch to a text field. Does it not for you?

Ah, if I select any random app, then I get the regular configuration screen, including that button. So now I did it, enabled "use root" and got this:

11.50.24/E add wait type KillApp1 time 2147483647 11.50.24/E add wait type KillApp1 done 11.50.24/E add wait task 11.50.24/E Error: null 11.50.24/E Index: 0, Size: 0

Same without root. "Done" and "Error: null" sound like it worked, but it didn't, the UI stayed on the screen. The last two lines were also coloured red. BTW, there's no visual feedback for the copy button on that error.

What happens if you use the package name of a normal app?

That works, except if it's the current foreground app (or one of them, with split-screen), then nothing happens.

So, to clarify, if an app is open in the foreground, it can't be killed? 🤨 Weird. 

Could you please try using the "Run Shell" action instead with this command:

am force-stop com.my.app.id

That's what Tasker is doing in the background actually...

In the Run Shell action enable the root option and set the error output variable and check it after the action to see what it contains. Thanks

That command works for a regular app in foreground and background. I set StdErr to "%Err" and later made Tasker show me a notification with that as its content, which shows up as a literal "%Err". I guess that means it's empty? Same with StdOut.

If I use com.android.systemui, my home screen background image resets! But it doesn't actually do the full "screen becomes black, then comes back without notification+navigation bar, then those come back" routine. And only if that happens does a certain bugged state of SystemUI get fixed which I'm trying to automatically get rid of. Executing this command in any other way (MacroDroid, 3C, "Secure settings", …) has the same result.

BTW, I'm having issues with that in other apps as well, so that part is probably not Tasker-specific. MacroDroid's "kill app" and "kill background process" actions also fail at this, as well as "3C toolbox"'s "kill predefined apps" shortcut, even though pressing a button manually inside 3C does work. I'm still surprised why SystemUI doesn't appear at all in the app list.

Unfortunately I can't help with those behaviours, sorry! As you said, it's the way the system works and is not related to Tasker. Thanks for the extra info!