Elektron Musical Instruments

I bought a new Remote SL keyboard and tried to control the joystick 
with the x/y-pad. In particular for up and down I get very annoying 
artefacts in the sound on the mono, as if it cant process all the midi 
comming in or something. To be clear, I manually go to the filter page 
and twist the lp-cutoff and it behaves as it should. Then I set it to 
50% and assign lp cutoff to the up/down joystick with +64 and use the 
x/y pad on the Novation instead. The sound becomes very strange with 
highly audible digital artifacts and distortion. I have checked nothing 
else is assigned to the joystick and I have recorded my x/y midi in 
Cubase to check the x/y-pad isn't sending crap data. I have no clue 
what is going on. Any one else had this problem or general 
recommendations on how to get this to work? OS is 1.08b.