After updating to the latest version, Dorico enables WinRT MIDI (that supports bluetooth) by default. For people with older hardware, this can mean that normal MIDI ports disappear in Windows, keyboard is hidden or renamed, routing is broken in templates, etc.
It took a couple of hours to find the culprit, but this bit from Cubase provides a good explainer:
I lost all MIDI ports (they were either renamed, or a new number got added to their names for virtual cables and of course the endpoint doesn’t recognize them any more) and my keyboard was not received by either Cubase or Dorico.
But it thankfully took only a few more minutes to discover in Version History that this lovely new feature can be turned off in Dorico Preferences:
Sharing in case this happens to someone else and they might look on the forum first to save time.