The Studio Special Editions are very old now - not that there is anything wrong with them, but VSL tweaked their templates for those libraries for an early 2010’s laptop in terms of power (which wouldn’t handle the slightest load by today’s standards). So unlike the newer libraries, they have the VelXF turned off by default because they don’t want to overload some antique laptop that someone is still using from 2011 or whatever.
So they expect the user to turn Velocity Xfade on by adding a CC28 value of 127 in the CC28 lane of each instrument as shown here: https://www.vsl.co.at/tutorials/guides/dorico-integration/quickguide#dynamic-control
That way if it starts to overload your antique laptop you can turn it off again by setting CC28 back to 0, but any reasonably modern system it is unnecessary and it can just be turned on and left on. Almost nobody today is still using a laptop from 2010-2012 era as their daily driver.
For their newer libraries you no longer need to do that in Dorico, they have VelXF enabled by default from the start.