Unity Editor freezes while closing

Hi,

we developed a native library, which depends on additional third party libraries. We can use our library in Unity, but every time we try to close the editor after using our processing pipeline, the editor freezes and has to be closed with the task manager. I checked the loaded DLLs of Unity before and after executing our library code and noticed that three DLLs, which are not dependencies of Unity, are still loaded:
C:\Windows\SYSTEM32\CONCRT140.dll
C:\Windows\SYSTEM32\MFPlat.DLL
C:\Windows\SYSTEM32\RTWorkQ.DLL

How can I manually close these libraries. Do you know other tools or have other ideas to check what prevents the Editor from closing?

Unity Version is 2017.4.1f1

Just a guess, but have you tried running Unity as Administrator?

Thanks for your reply. But this doesn’t do the trick.