That’s so weird but this exact thing just happened to me! I was doing some tests for another thread, for this I had to forcefully crash Dorico using Task Manager. When I reopened Dorico it offered me to open the file that was auto-saved. It opened with everything correctly configured: A simple Piano routed to Kontakt, I pressed Play, Play from, Replay, etc. nothing happened! I pressed on Kontakt’s own keyboard and it played loud and clear. I used Kontakt’s own MIDI Monitor and it was receiving no signals from Dorico…(?)
1.- I replicated the experiment by crashing Dorico again and got the same result.
2.- Daniel I also created a new project as per your instructions and it worked fine. I then went back to the restored file and it still didn’t work.
3.- Opening the original file (not the auto-saved one) also worked fine
Another final thought, when I spend a lot of time without playing anything in Dorico it often cuts off when I play again after say half an hour or more. Almost like the plugin goes to sleep or something…