Unreliable sound with noteperformer 3

Hello

I’ve been using the free trial version of Dorico Pro 3 for about ten days and I’m having a persistent issue with sound using Noteperformer 3. I’ve set Noteperformer as my default playback template, and it shows up as the playback template/VST when Dorico is in ‘play mode’, but I seem to always have to open Dorico, change the playback template to one of the built in options (in play mode and in preferences) change it back to Noteperformer, then quite and relaunch Dorico before I get any sound. Seems to apply to any project. FWIW I’m using a MacBook Pro with os El Capitan. Any thoughts welcome!
Thanks
Lucy

Maybe too simple a question, but do you save the project after applying the NotePerformer template?
Could you make a simple demo project and post here? From the project data we can get a clear picture.