ims 20 lowpass filter problem

[tok0r]

hi guys. i'm completely new to ims, or any other korg product.
i have a problem with the lowpass filter in the synth. i can not adjust the value at all, it always resets to '10' after i turned the knob.
am i missing something?

regards

edit: when the pattern isnt playing back, it's working properly. but as soon as i start the playback it resets to '10'.