MIDI input not recognized _only_ from a particular keyboard (Keystation 49)

I have a few USB MIDI keyboards connected to my Mac, and two of them are able to play sounds on software instruments (and, generally, their input is seen by Logic), while one of them (a M-Audio Keystation 49) is not.

Some of the diagnostic things I've checked:

• I'm seeing notes and control messages appear in MIDI Monitor (a separate MacOS app)
• The Keystation devices (the keyboard, itself, and the transport controls) both show up in the Input Ports in the MIDI Environment
• I don't get any notes played even when the Keystation is sending on the same channel as other keyboards which are playing sounds (so, this isn't something where a certain channel is getting ignored)
• Here's the really weird part: In the MIDI Settings->Inputs, Logic sees both of the Keystation devices. When. Turn the checkbox on/off, Logic adds/removes some tiny little columns in the Arrange window. Turning the "Transport" checkbox on/off turns on/off a sliver of magenta which seems to follow whichever track is currently selected. Turning the "USB MIDI" checkbox on/off turns on/off a blue sliver which seems to span some number of tracks.

Because of this behavior in the Arrange window columns when I enable/disable Keystation inputs (but not for other keyboards), I'm wondering if there's some special Keystation-aware plugin hiding within Logic that doing special handling of data coming from it.

Any idea what's going on, here?

[Edited by Moderator]