Random detuning different instruments in NotePerformer

Has anybody had problems with tracks suddenly and randomly detuning?
Happened in Dorico 3.5 and Dorico 4

Welcome to the forum, @Rupert. I think NotePerformer responds to all manner of MIDI continuous controller values. Have you got any recorded continuous controller data showing in the automation lanes in Dorico’s Play mode? Do you have a MIDI keyboard or other MIDI device connected to your computer that could be sending spurious controller data in? One way to see whether that is the case is to look at the very bottom right-hand corner of the project window: if you see a green dot on there continuously or flashing when you’re not playing on your MIDI device, then Dorico is receiving MIDI data from somewhere, and you should probably figure out where!

Thanks Daniel. I will investigate.

Curious?
I have disconnected the keyboard.
No spurious midi coming through
Can’t see an automation problem.
Which CC will I find it under?

I’m afraid I don’t know. Please consult the NotePerformer documentation for which controller values could have an effect on tuning or pitch bend.

Thanks. I will keep investigating.