Keyboard won't work on LMMS

Having trouble with LMMS? Ask about it here.
I have an M-Audio Keystudio 49i that I use for composing on LMMS. It's worked countless times on LMMS until recently.
I pick a track, and set my keyboard as the MIDI Device to play it, right? After all of that is done, I press a key on the keyboard and nothing happens.

Why does this happen?
What do you mean by pick a track? You mean you set the MIDI input on the instrument track? What version of LMMS are you using?
Yes, that's what I mean. And I have 1.0.3
No idea why, really, especially since "it has worked countless times before". What did you change? https://lmms.io/documentation/1.0:Using_MIDI
Idk what I changed. It just stopped working. It could be the keyboard itself, but that's running. It just cannot play any notes.
Does it crash if you create an entirely new project and don't try connecting it to a VST? The default TripleOscillator for example.