Why can't Tasker manage battery mode on my rooted Pixel?

Question

I've been using Tasker to mute my phone at work. I recently added some nested tasks to enable and disable battery saver mode when I arrive and leave. However, it doesn't seem to have permission.

The phone is stock rooted Oreo on the October 2018 security patch release. Tasker is up to date.

I first see a notification:

Missing Permissions
Tasker needs the following permission(s) for the funcationality you have configured:

Write Secure Settings

Tapping the notification, I then get a modal:

Missing Permissions
Tasker needs to have permission to write secure settings to use this action. Want to learn how to grant it?

NO OK

Then another:

Use Root
Since your device is rooted you can automatically grant this permission. Do it now?

NO OK

Opting for the affirmative results in a toast notification:

Tasker has been denied superuser permissions.

The battery mode never gets changed. Thanks for any assistance.

Answer 1

As it was confirmed in the comments, Tasker was denied superuser access in the Magisk app. Tasker can enable battery saver.

If anyone wants a command-line solution, try this:

Code -> Run Shell -> Command: settings put global low_power 1 -> tick Root.

Replace 1 with 0 to disable battery saver via command-line.

Tested on OnePlus 6 running Android 8.1.

Answer 2

If you use the Magisk app, add superuser permissions at Menu > Superuser > Tasker = ON.

That worked for me on Resurrection Remix OS with Android 9.