In my case, there are also problems with Waves VST3.
When I close a project and open another, Sonar X3b crashes every time.
But it works fine, when I close the project, close Sonar, and restart Sonar and then load the other project. This is an easy workaround for this problem.
Something from Waves seems to linger in the RAM Memory by closing the project. All projects are saved in X3b and it ist ONLY up to the VST3 waves plugins.
I have thes problem identical on three Computer.
Some crash reports were sendet a few days ago.