Unfortunately it is not possible to open it in any way.
Had to update the Mac to Mojave first. No reinstallation of Dorico 4 helped either ?? Possibly a bug ??
Eggi
Dorico 4 will not run (nor even install) on MacOS less than 10.14 Mojave, so it’s not clear what you have going on. The Ensemble picker works for me (also Mojave).
My computer is running Windows 10 and the Ensemble picker is working. I wanted to show the new function to my colleague on the Mac, but unfortunately there was no reaction when I clicked on the corresponding buttons. Only solo and tutti selection worked. Unfortunately I don’t know much about the MacOS 10.14, so here is my question why this particular function doesn’t work. 
Is it possible that your colleague has Dorico SE? Or another less full-featured version? I couldn’t find if that was a specific difference between versions, but it sounds like your colleague has a more limited version. Just a guess, though.
Eggi, is your colleague running Dorico on a multi-monitor setup? If so, try moving the Dorico project window to the primary display, then show the ensemble picker. We have fixed an issue with the ensemble picker since the public build, so if your colleague can show the instrument picker on his secondary display, the good news is that the ensemble picker will also appear in the same place on that secondary display when the maintenance update arrives.
1 Like
We have tried your comments. The ensemble picker works on the second display (only here). Thanks for the help with hope for an update soon.
Eggi