I have a simple drum score with a kick drum (voice 1 , stems down) and a snare drum (voice 2, stems up). For some reasons Cubase is putting the voice 2 rests BELOW the staff (highlighted yellow) rather than in the staff as I would expect (marked in blue).
This is because the voices of your lower and your upper notes in your staff seem to be inverted.
In this example, I guess the F is set to voice 1 and the C notes are in voice 2.
You can see this in your Polyphonic mode by checking the stems direction.
So correct the notes voices in your score, and set the stems in Voice 1 to “Up” and “Down” in voice 2 in Polyphonic settings.