First, welcome to the forum.
Question: when note chase is on, does the module see the various triggers when you strike them?
It's been my experience that he preview button produces quiet sounds. Hitting it harder/quicker will produce a louder sound. At least that's what I remember. So, when you hit preview hard, fast, and multiple times, does the sound increase?
So... you are getting the voices (from preview) out to your headphones, correct?
The module is not seeing trigger hits from the pads, correct?
The reset would change sensitivity back to default I think, so I assume sensitivity is ok.
With the module on, unplug a tom or snare. Did it trigger during the process of the plug coming out of the jack? If so, how was the sound level?
You do have your output to main (or headphones) right? And the volume is turned up, yes?
I'm not sure I have the answer, just trying to clarify and isolate the issue.