This ^ 1000.
I only purchased Cubasis recently and was looking forward to throwing a bunch of my favourite sample packs into it so I could get some writing done on a holiday in the near future. I have the same issue. It seems as though Cubasis cannot deal with user-generated subfolders. I can’t deal with all my folders being in the root folder, especially since this requires manually moving every individual sample into their folders using Files App (which is very slow), as Cubasis throws everything into the Audio/User directory without maintaining the original folder structure.
This issue could really use some attention, Steinberg pals! (Unless we’re doing it wrong, of course. In which case: pls send halp.)