Video (sorry about the shoddiness)
Changing the lines/beat in the song makes the sustain end up on different parts of the envelope.
Restarting Renoise didn’t change this behaivior.
Definitely a bug where LPB=1.
Even when Sustain is Off you get no sound with a similar envelope to your example (p0=0%, p1=100%, p2=0%) with LPB set to any other value you get a quick pulse of audio, as expected. With Sustain set to On then you see the green position bar stays on p0, rather than to p1 where you have set it.
As the Envelopes are meant to be 24 points pre Beat the LPB should make no difference, and comparing LPB=2 to say LPB=24 and there doesn’t seem to be, only LPB=1 seems to have an issue.
I know there have been previously reported issues with the Envelopes not quite working as logically expected under certain conditions but I can’t remember the exacts of these…
Yes, the instrument envelopes, but i can’t find that topic either anymore. But it had to do with the value of the first point in the envelope not being applied if the second point follows right next to it. Might as well be something with interpolation not being applied.
Here’s another thread with the same bug reported and an example song. I can’t say your reply to it really makes sense, not with Instrument Envelopes which must start on the first point to be useful, nor with the fact the behaviour is only like this when LPB=1 and the number of points is per Beat, not per Line.
Unfortunately no comment from a core Dev…