Honestly, I’m starting to hate this keyboard. Weird behaviour, a sustain that sometimes kicks in without pressing the pedal, a meh velocity response and these maddening CRYPTIC error messages, that pop up even without ANY Keylab outputs activated in Ableton.
The message suggest your keylab is set up wrong in your DAW. This can perhaps give midi feedback, that can create strange behaviors.
Try and go into your DAW setups and do like the message suggest.
Does it perform as expected in Standalone? If so, it does suggest a DAW issue. I am not an Abelton user but as suggested, a screenshot to its MIDi setup may help.
Sorry for the late reply, work got in the way. I use Ableton and while admittedly I was pretty annoyed at the new and obtuse error message, the thing is there are two DAW Midi Output preferences in Ableton and that threw me off, since the error persisted when I disabled all outputs. (But in the wrong spot as it turned out)