I know this might be an old topic, but after my recent experience, I thought it might help.
I recently loaded the East/West Composer Cloud Collection, and overall, the samples sound great; however, while testing a few tracks, I couldn’t help but notice that certain notes would hang during very simple, slow, whole-note passages. Nothing that required a Panic Button reset; playing the hung note was enough to cancel it out. But this would be unacceptable under any circumstances, and so I set out to find the culprit.
I started by opening the East/West Play app to see if this was also happening here. Nope - all notes start and stop as they’re supposed to in all collections. That brought me back to Cubase (using C8 Pro here). I read the suggestions here, and about the only one that seemed to apply was unchecking Aftertouch. Still, that didn’t make any difference either.
Out of curiosity, I took a look at my MIDI Input setting - it was set to All MIDI Inputs. I then changed it to my main input (M-Audio Fast Track Ultra) - voila! 
No more note hang. Anywhere!
This is one of those moments when it might seem easy to pounce on either East/West or Steinberg - but at the end of the day, the culprit was something small and stupid that we users could control. Hope this helps.