Where are the parent materials? (Datasmith C4D import)

The Datasmith C4D import works really well. But all i get at the import are material instances. Which would be totally okay, if i could find the parent materials of them. Where are they hidden? When i try to use “find parent” nothing happens. In the material instances the parent materials path is named “/DatasmithContent/Materials/C4DMaster”. How do i get there? The “browser to …” function doesn’t work. It seems to be an invisible folder?