Sorry if this is complicated; hopefully I can explain it well enough
Install a virtual loopback cable. (for me its LoopBe30 64 bit on windows) Create about 20 VST tracks in a DAW (Using Reaper at the moment). Connect Dorico staves to said VST in Reaper using Dorico’s MIDI instruments section. Also have a MIDI keyboard with input/through set in Dorico only. This setup worked great in the beginning, but it seems like I’ve crossed some kind of line as I add.
Selecting any random stave in Dorico, Play some keyboard notes and the corresponding VST responds immediately and cleanly in the DAW.
Press play in Dorico - and the playhead likely won’t move, though sometimes it will after repeated start and stop of the transport. Mute all midi channels though in LoopBe30, press play and the playhead moves in Dorico. Quickly unmute the channels and all is well, at least until you stop the transport. Note that at the beginning of playback you will always see MIDI flashes on all channels. Using a MIDI logger on the insert, I can see that every channel gets several setup messages like volume, pan position, pitch wheel position, MSB, etc. when play is pressed, even when the playhead doesn’t move. But it does not get any note on/off when the playhead is “stuck”
I spend a lot of time thinking the issue was some kind of contention over the ASIO driver, or audio engine or whatever. Tried all sorts of things like pointing the DAW to the generic driver which is connected to the icky laptop soundcard, and Dorico to my Scarlett. Started with a silence template before adding MIDI instruments and made sure there was no actual audio out from Dorico. Tried putting the DAW on WSAPI and other weird settings I could find. None of it seems to matter. And IT SOMETIMES DOES WORK correctly, where I think an audio contention issue would always fail?
Can send the diagnostic if you want.
So questions: Is there some kind of MIDI handshake where the DAW isn’t responding right? Why would Dorico be stopped like that? I’m not assuming the issue is Dorico.