I have the same problem.
I use Cubase 5.1/Win XP64 on the DAW. On the server side: VE-pro, Win XP64, Kontakt 3.5 with LASS library.
Behaviour:
Stuck and/or missing notes (or at inconsistent volumes) when playing LASS strings LEGATO patches (obviously with the LASS legato Kontakt script). Never happened with any patched that don't use the legato script.
Repro:
I open a new VEP instance, label it (so it is preserved), load a Kontakt 3.5 and load my LASS multi. I connect to this server through network from Cubase 5.1. Then I get the problem (see above). If I reload the Kontakt Multi (which takes some long time!!) then everything is fine - no problems. Please note that while reloading the K3 multi I haven't touch any VEpro connection stuff.
From this point if I save Cubase's project with the connection to the server made (active), close the Cubase and then reopen the saved Cubase project (obviously the connection to the server is automatically done) -> I got the problem. I would have to reload the K3 multi, without touching the VEpro connection (again some long waiting time!!) - fine.
The only way I could get the VEpro server keep the multi in a "uncorrupted form" is if I disconnect that particular VE pro instance (from the VEpro plugin), and THEN save the Cubase project. Now everytime I open that saved project, and then (obviously) making the manual connection to the VEpro slave instance, it works. The LASS kontakt3 multi on the server side remains "uncorrupted".
I hope this problem gets sorted out; the reason why I got VE3 (and VEpro) was that I wanted to merge my extensive VI library with the LASS strings, on the same computer.
Thanks!