well, SX 2 is not "officially" supported for the VC, AFAIK. so perhaps certain problems might be SX2 specific.
on the other hand, the VC still have some considerable bugs even using the latest Nuendo and SX3 builds. I still have arp timing problems, the occasional stuck notes and often loosing sound when fiddling with the delay types in VC.
This makes it hard for me to trust the Ti in realtime work situations. hoping this is will be fixed soon.
Best,
midi.