Hi nytjadens,
I’d echo mate-redundant’s comments but with respect to DM1. I had the same issue and the same solution - selecting ‘virtual MIDI’ seemed to get things working - both for MIDI in from DM1 to Cubasis and when sending MIDI out to DM1 from Cubasis.
Also, you need to make sure that MIDI notes to/from Cubasis are active within DM1’s MIDI settings…
Hope this helps? Good luck…
John