Allowing Transfer of Student Repositories after assignment is created

Main Question: Is there a way to enable administrative permissions for an assignment that was created without them so that students can easily transfer ownership of repos? Barring that, what is an alternative for allowing students to take ownership of their repos?

Background: I am currently working with my students to transfer ownership of repos from our organization account to their personal accounts. This is generally pretty easy to do because I check the box to give student’s admin rights upon assignment creation. This gives every student the settings they need to transfer the repos. However, my course assistant forgot to do this for about half of the labs and I am now trying to figure out how to enable this. There is a note, under the checkbox for this that says editing it after the assignment is created will not retroactively alter permissions.
Screen Shot 2020-10-07 at 2.22.37 PM

I figured I’d try it anyways (since I don’t have any better ideas) and got the following error message: Invalid repository selection, please check it again.