Chris Livingstone on Drag and Drop Issue in Cubase Pro 9

A recent convert from Pro Tools to Cubase Pro 9.
I can drag any and all midi files from my Superior or EZD without issue.
My problem occurs if I want to drag/add a "fill" midi file to an existing midi file already in the project.
It visually shows it's there but with an odd cross hatched like pattern and when playing back is all phases like it's trying to play the new part and the part beneath it.
Grid and snap are activated and working as expected.
I could and did work with his way in Pro Tools without incident.
I've posted on the Cubase forum but thought Id try my luck here too 😉
Thanks