I have the same problem now, not with NotePerformer but Kontakt 5. I know, there are other threads about this problem, but I didn’t find a solution there. So I hope here is the right place.
My system:
Latest Win 10, Dorico 3.5.11, Kontakt 5, FastTrackPro ASIO driver.
All installation paths are default. No other VST plugins are installed.
Standalone Kontakt works.
Problem:
After choosing Kontakt in the Preferences and moving the VSTs from blacklist to whitelist:
Kontakt still doesn’t appear in the VST instruments dropdown in PLAY mode.
What I tried:
Reinstalling both, Dorico and Kontakt 5.
I removed the folder Dorico 3.5 AudioEngine_64 completely.
After restarting Dorico, in the newly builded folder: Kontakt ist still in the Vst2xPlugin Blacklist Dorico 3.5 AudioEngine.xml. Strange: inside the programm it is listed under whitelisted plugins.
I’ve read this post : Dorico 3 Elements doesn't recognize Kontakt 5 or 6 - Dorico - Steinberg Forums but I couldn’t find any solution which works for me.
I’ve uploaded a diagnostic file here: Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.
Thanks for help,
Peter