I can confirm this, although not with total confidence. I just installed 10.9 and fired up Logix X and VEpro. Everything seemed fine until I held a chord on an Ivory patch which resides in a 64-bit VEPro server. The chord played but after a second or so it cut off abruptly. I saw your post, disabled "napping" for VEPro, relaunched VEPro, and now all is well.
Also, when I first experienced the problem i switched over the the VEPro app to see what was going on. Everthing was fine. Of course VEPro then became the frontmost app, and therefore not "napping" . WHen I switched back to Logic everything was normal for a few seconds, and then the bad behavior returned.
So... turn off the napping!
Hope you are well, Jay!
Steve