It is not the issue speciffic to roland. I have Black Hawk HXD III e-drums and the issue is the same. This issue is not specific to BFD or Superior Drummer too, because I use Slate Digital SSD4 and SSD5 (vst and au versions) and it is the case with every configuration (I checked it with windows and Mac, because i'm very stubborn and it is my goal to make it work.
By the way Slate Digital SSD5 vst has a free version with one drumkit, so everyone can try it out (no expiration date).
I tried almost everything:
quantization on/off note repeat on/off
Windows version of ALK2
Mac version of ALK2
Factory e-drumkit reset
Changing midi mapping in e-drumkit
Changing midi mapping in SSD4/SSD5 vst/au versions
Changing midi input devices (straight USB connection with e-drums, using midi-usb roland device, connecting via midi cable to my midas mr18 mixer-interface)
changing buffer settings
changing kits in e-drums
If I manage to get it, I will try it with some other e-drums module. And report the effect.
every other audio software on windows mac and ios (ipad and iphone) is working with this drumkit correctly (reaper, logic, cubase, mainstage, garageband)
I suspect it could be an issue with note-off midi communicate (but it is only one of my speculations), because if You take a closer look at ALK2 when drums are in midi-recording state, You will see that notes are changing it's duration, like You would play a note on piano and hold the key. From the time you hit a drum, the graphic note representation in ALK2 is getting longer and longer, even when You not playing anything. It is also strange, because even when ALK2 is done recording and it pass to Playback state, the note lenght is still getting longer and longer (it is changing its duration even in playback state and You can see it on Your own eyes. If what i suspect is true, software could be "thinking" that for example one snare hit is lasting (with no end) to the end of track, so You can't really hit it again, because the note is still on. I think that could be the case. I dont really know why the note is changing it's duration in playback mode too.
Take a look at midi notes: