Midi in working, no sound out with one keyboard only

[Merula]

I have an M-Audio Venom which was working as normal as a midi controller. Suddenly there is no sound coming from the Minitaur although the light is showing that it is receiving midi information. Two other keyboards work as normal with sound coming out the Minitaur. I'm assuming then, that it's the Venom. When I plug the Venom into another keyboard it is working normally. Any clues?

[Stuka]

Any chance you did something to change the MIDI output channel on the Venom, OR possibly sent an inadvertent program change message to the Minitaur?

The Minitaur only reponds to a single MIDI channel, and by default it's channel 1
(some keyboards / synths / plugins respond to "OMNI" by default, which is any channel).
The LED could indicate it's receiving MIDI, just not on the correct channel.

Concerning the inadvertent program change (which is possible if you have updated the firmware and using the v2.0 Editor) -
Here's how to return to "panel mode" per the manual:

"Hold the GLIDE button and press both VCO 1 and VCO 2 buttons to return to
panel mode (Preset 0)"