Should I add you to the list of people interested in being able to decouple an instrument’s untrigger conditions from its trigger conditions, to the list of people interested in being able to trigger an instrument only from its left edge, or both?
Absolutely both 
I’m afraid I haven’t been able to reproduce this behaviour here. When I try, the instrument plays as normal. Could you describe the trigger conditions of the instrument in more detail, and possibly post a screenshot? There may be some detail of how it works that I’m overlooking in my test case.
Turns out being the problem below. If you can provide some place where to drop my project as a zip, I am happy helping you to reproduce the error.
Quantization bug / floating point ‘equality’ issues