MIDI keys no longer recognized by Dorico

My setup has NOT changed. M-Audio keyboard has until this morning been recognized by Dorico. Restarted Dorico, restarted computer, changed input for keyboard, checked the Preference—Keystation shows up. Other apps [Finale, Logic] recognize keyboard—so the keyboard and MIDI setup is working.
I then updated to 5.1.81.2225 to see if that helped—although, Dorico and the keyboard have been friendly from the beginning without any intervention from me.

Why did it stop? What’s my solution? 'Bout to panic…

Quit Dorico again and restarted it. This is what I get now:

Restarted everything again. Keyboard recognized by Finale, Logic, MIDI monitor, everything but Dorico. Dorico shows Keystation 61 in preferences, but no communication.

Sorry to hear about this problem. I can’t think of anything that has changed in this update that could have caused this.

Can you try quitting Dorico, then in the Finder use Go > Go To Folder to go to the application data folder:

~/Library/Application Support/Steinberg/Dorico 5

Be sure to fully reproduce the line above, including the leading tilde (~) character, or you won’t go to the right folder.

Try temporarily renaming your preferences.xml file to something else, e.g. preferences.old, so that Dorico won’t load your saved settings. Restart Dorico, and see whether MIDI input now works as expected.

If not, you can quit Dorico again and restore your original preferences.xml file. After restarting Dorico, try deactivating the checkboxes for all MIDI devices except your Keystation keyboard.

Restarting did not help. After a few hours of searching, I found a box in preference where MIDI input had been unchecked. I have no idea how, since I hadn’t opened preferences in weeks, and certainly would not have unchecked that!
Is there a way to delete this short post since problem solved?

No need to delete it – and it might even be useful to somebody else with the same problem in future.