MIDI track records as flatline and disappears immediately after recording!

Help! As of last night, when recording midi, the visual in the region is just a flatline, and the region disappears as soon as recording stops! I haven't changed anything. What could be the matter, and what's the solution? Thanks!

 

Edited to add: Sound is going in to Logic Pro because the green "VU meters" on the track are registering that it is. So the connection from my keyboard to my Apogee Duet to Logic would seem to be intact. Yet nothing actually records. Have tried a relaunch of the app, a turnoff/turnon of the keyboard, and a reboot of the computer to no effect.

Recording enabled on the track? Correct MIDI channel selected? If you see meter movement but nothing records it suggests a disconnect in the signal chain.

Thanks. I had a divine revelation while driving around this afternoon, which was to remember how, in the past, with completely unrelated applications (like Word), the solution when something went screwy for no good reason was to make a duplicate of the file and use the duplicate. In fact, the duplicate Logic file does not have the problem. Fingers crossed it'll stay that way.

Been there. Logic unfortunately bestows such inexplicable candy on its users every once in while. I've got one project file that will reliably crash my entire system. Had to use an earlier version and re-do things to recover lost ground. Since I don't know the origin of the crash I'm leery about removing the project file, so just tagged it with a nice big red dot. Hope things remain calm for you.