You have to open the editor and make sure there is an incoming audio source of some kind (e.g. pings from the WP). I’m still not able to get MIDI out of my WP so I went a slightly different route…
In Ableton, I put the M4L device on a new track. I then made an audio track, put a Vinyl Distortion on it with a really low density (~0.04) and volume all the way up. I then set the output of that audio track to the Wing Pinger Resonator MIDI track. Then, click on the “Open Editor” button on the M4L device and in the top right set audio input to receive from the audio track with the Vinyl Distortion on it. It’s a really cool sounding resonator and you could ping it with virtually any kind of sound source!
Now I just to figure out with TRS → MIDI cable will actually work with the WP…