Thanks for the bug report.

About duplicate tool:
This is a known issue.
For some reason on some devices this fails to instantiate if the GameObject is hidden in the hierarchy.
To fix this Edit / Project Settings / Ultimate Editor Enhancer / Hide Temporary Objects of Duplicate Tool - OFF.
I'll add a description of this issue to the documentation, and consider turning this option off by default.

About pivot tool:
You cannot change the pivot for objects that contain a content (such as an Image or Mesh).
Wrap your object in an empty GameObject and change the pivot for the outer GameObject.
This is written in the documentation:
https://infinity-code.com/documentation … pivot-tool
I'll add a warning about this to the console when attempting this usage.

I opened an empty project with Unity version 2021.3.15f1 and tried to use the duplicate and pivot tools on a cube game object. These tools are broken. The duplicate tool does not create duplicated objects in the hierarchy. I can see them in the scene view and I can save the scene in that state. But after restarting the editor, they are gone. When using the pivot tool, holding v and clicking on a vertex just move the whole object to that point. The tool remains on and does not toggle.