I have a sample library that I created that has this problem. I recorded a track with some long held notes. It worked fine while I was playing it and for the first 3 or 4 times playing it back while adding other tracks. Then all of a sudden it started having notes drop out before they should. I noticed that the Disk Meter in Kontakt flashes red the moment each note drops out but stays at zero percent. I looked this up and found other users had identified that it happens with some samples when they reach a looping point. I also heard that it has been a recognized bug for a while but is notoriously hard to reproduce, making it difficult to troubleshoot and fix. Well, I have a sample library and a project in Logic that seems to be doing it fairly reliably. When it first started happening I was able to save and close out of Logic and then reopen it and it started working again. But within about 3 or 4 playbacks it was back to dropping notes. I've done this a few times and it is the same each time. So, if it will help with this bug I'd be happy to share the Logic project and the sample that is having the problem. Could this be of any help?