Finally got the licence working, and the first project I booted up shows a wacky error with my Flutes!
I have Spitfire BBSCO Core flutes playing a simple legato line.
Sounds fine and delicious in Cubase 10.5 but in Cubase 11 it’s all over the place and even missing notes!
After a rummage around I have determined the issue is that track had a MIDI Modifier on it to transpose up an octave.
Loading the project in Cubase 11 caused the scale setting on the MIDI Modifier to change from “No Scale” to “Locrian”. And that just didn’t work with the rest of my track or the instrument range
I assume this is an unexpected side effect of the new scales stuff.