Dragging midi removes from the sequencer page

This seems to be hit & miss (maybe I’m doing something wrong)
Sometimes when I drag a midi segment from scaler into my DAW (cubase pro 14), instead of copying it over it moves it instead, so the midi is no longer in scaler, I then cant subsequently get it to go back. Am I doing something wrong here ? It doesn’t happen every time, but it has happened enough times to be annoying. Is this a bug or am I missing something ?