cubase 10 rewire with reason sticking lagging notes!

cubase works fine using rewire with reason until I try and record midi notes on top of a track already recorded.
when recording a new track while no other reason instrument is playing on that track there is no lagging…its as soon as i want to add note to it ie…creating a drum pattern…start off playing a hi hat is fine, then adding snare the notes stick and lag.

it is ok if separate reason instruments are playing its just when trying to record on top of same instrument.

hard to explain but if anyone can help.