I have just installed the latest update for Omnisphere (Patch and Software).
When I try to run it in VStack, the program stops loading when it scans the Ominsphere plug and gives no error. It just returns to the desktop.
When I take the Omni dll out of the steinberg vst folder, VStack loads fine.
This problem never occured in any previous versions of Omni.
Using Omni in Nuendo does not cause this problem.