At this time, there is no specific tool or process to copy rubrics between Ultra courses. However, this workaround may be useful to faculty who want to copy rubrics between courses.

Creating Categories

Tip: To avoid duplication in the gradebook, make sure the assignment is not using a custom category.

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Create a hidden assignment with a clearly identified title for your rubric copy. In this example, the assignment is called Rubric Copy.
Attach the rubric you want to copy to the assignment. Due date is optional. You do not need to provide any text for the assignment or other parameters as the sole purpose of this assignment is simply to copy it into another course.
Save the assignment.
Go to the course where you want to copy the rubric.
Click the overflow menu (...) to access the course copy tools. Select Copy Content.
Search for the course where the rubric assignment resides.
Select the rubric assignment and nothing else.
Copy the rubric assignment. You may get some error messages during the copy process, but it is probably safe to ignore these.
After you verify the rubric is in the gradebook, you can make a duplicate or use it on another assignment.