O-keeee, I got it working now :-)
The problem was that I have one single XCode project with several targets, and when I did copy the Voices folder to my project, it got added to only one target, so the voice files were missing in the bundle resources (Build phases -> Copy bundle resources).
So the problem had nothing to do with architecture, singleton or VCs.
Thanks for your good support, and expect an order for the full version next week, but for now, time for some more test, and… party.
With kind regards,