I was lowering Lines/Beat to 1 to make song slower, and then some instruments did not play at all. It has something to do with volume envelopes starting with zero value and having sustain right next to it. Envelope play position wont meet sustain, just stays at beginning. Ok, it’s kinda hard to explain. Here is file/pic:
3948 
Is this bug or just some logic I don’t get?
The envelope init point should start a little later than point “0” or an exact point. This is also a problem in other envelopes (instrument envelopes, envelopes in native devices).
In the automation envelop, you can zoom in and simply draw a start-node on 0.1. That should work. With the other envelopes this level of integrity is not available.
With LPB 1 this indeed turns pretty noticable. This behavior has been reported before, it is still not clear whether this is a bug or a necessary evil.