I discovered today, with stereodelay, but idem with others third party.
IN STOP, WITHOUT PLAYING
1 - Put a stack, and a delay (on stack insert or on fx slot, the same.)
2 - put the feedback of delay at high level
3 - supposing is a digital piano, a sound, play a note, and delay start to produce many times…
4- while note are playing by delay many times, SWITCH to another song, or another part.
5- come back to the previuos,
THE STACK is now mute, no receiveing sound, blocked; only the queue of delay goes than blocked.
Must be jump up and down other song or part, and remove the delay, or turn off the feedback into very short value to restore stacksound.
In short: if delay is long, and you switch to another song while delay is playing, (during the queue of the feedback by delay) the stacks is mute, can’t restored easy. you have to wait the queue of the sound , to restore.
If you come back into the part (with delay) you have to wait that NO sound goes , the feedback goes down and now, you can jump up and down to another part, and back to the previuous that finally restored.
There is no real solution, as VST Live tries everything to keep things running.
Possible actions would be
a) to unload and reload the plugin and all of its settings. This would certainly cause performance loss, even when performed in the background. Most of all, if you were to switch back soon, it might not have made it yet.
Basically however this would be sort of a purge mode, which we are planning anyway, means that when a Part is de-selected, it will release all plugin instances, preference
b) continue to run the plugin in the background until it doesn’t produce sound. This is kind of an extended Layer Sustain which you can find in preferences (and should test in the first place). However this also possibly creates CPU problems.
…but now I see a different problem, actually what you described appears to be a bug: the rule says, that as long as there is sound, the stack needs to continue to play for overlapping and not suddenly muting sound. But when you go back, observing the stack for output silence needs to be switched off and input re-established, will check and eventualls fix, and that will most probably solve your problem. What I said before is a different issue (mostly for Layers).
Finally…I remember there was a problem of this kind, so looked up the code and it appears to do the right thing. Then I ran your test exactly as you proposed and connot reproduce the problem. Did you try again with the latest version?