Getting an error when I select "Include approval step"

[Tyler Simecek]

In an existing workflow, I am trying to view/edit approvals by selecting the checkbox or 'edit' next to the "Include Approval Step" I am getting an error below (screenshot attached):

"Unable to load approval options

We weren't able to load the options for this approval step. Error: Workflow was not found."

I have tried to delete and read the workflow and the statuses but still get the same error.

[Jack Brickey]

Hi Tyler,

Is this a active workflow? Can you try to make a copy and see if you can edit the inactive copy?

[Krishna Raghavarapu]

For in active its not showing add approval option 

How to solve this error, same error facing.

Please us to find solution.