When a use case is copied, then duplicated into a project file from a referenced project, the ability to edit the use case details is disabled. Any use case created in the project has a blank Details tab. The only option if details are needed is to delete the project, start a new one and manually recreate the use cases that are needed.
I just checked on the latest build on v11.2 but seems cannot repeat the problem you experienced. May I know what is the version VP you using and what is its build number?
I have attempted the same in Version 12 and I get the same bug. If I duplicate a Use Case from the Referenced project, I now get none of the Use Case Details and it removes the ability to create a use case detail entirely for the entire project.
This is critical to our usage of the software and ability to reuse artifacts.