Assigning multiple instances of the same VSTi to different controller pads

I have been using Sample Magic’s Stacker VST with multiple instances, each one assigned to different MIDI channel/pad (I’m using an Akai MPD 226 as MIDI controller), so that I can trigger each drum independently (and play on the pads at once). This is possible in FL Studio since version 12.3 (check the video at around 08:00: See attachment1.

Since I moved on to Cubase 9 Elements recently, I just can’t figure out how to work in a similar way as before, with 3-4 instances. However, I see 4 MIDI channels for MPD in Cubase (See attachment2). MPD seems to be A1-A16, MIDIIN2 B1-B16 on my controller (which has overall 32 channels)

So, it seems like I can only work with two assigned instances, or have I missed something?