Thanks for the speedy response and fix Ulf! The project file works great now.
Yes, that is weird, I have no idea what could be causing this. In answer to your questions:
Do you have your computer running for days sometimes and not closing Dorico but only changing projects?
No, never – I shut my computer off every evening or when I leave the house, and also usually restart entirely when I run into weird issues. By working on it a long time I simply meant it’s a file I’ve been regularly accessing for a few months. It might be worth noting I also tried a previous backup file (from when I knew it definitely worked) and that still was giving me the issue!
Can you give some other hint of what you are doing especially with that project?
The only thing I can think is that occasionally, when NotePerformer’s sounds do not satisfy what I need, I have added a separate VST in the play tab using Kontakt 7 (Sample Modeling Strings). I do this sometimes for more complex parts which NPPE cannot handle as well. It is possible some of the flows were connected to Kontakt for a staff or two, while most of the time I do stick with NP. I think that’s about the only ‘unusual’ thing I can think of which would be related to the audio engine specifically (but I often do this on all my other projects too). Let me know if that is helpful, and thanks again!