It seems that no matter what you change in the mixer, solo or mute, all the instruments keep on playing. When it seems to be working, for example, while soloing the first instrument, the other instruments are still playing softly in the back ground even while they all are set to mute and the volume slider is totally down.
Using the Play engine, I created a good working expression map for EWQLSO solo strings. Everything worked great and the correct articulations were played until suddenly… it didn’t any longer. During writing music in the score, the wrong sampled got triggered, trills instead of the normal legato. I checked the Expression map which is still OK, so it should work… I was able to fix this by going into Play and clicking the first key switch on the keyboard.