Sorry for asking something about the old Mobius 2.5. I have a script that toggles Mute for a track. The korg nanoKONTROL2 can have its lights controlled via MIDI commands, which I verified via the command line using sendmidi:

sendmidi dev nano ch 16 cc 42 127 # turns STOP button LED on
sendmidi dev nano ch 16 cc 42 0     # turns STOP button LED off

Here's my mobius script (using MidiOut):

!name toggle_vol_track

variable track prevOutput

variable track ccn

set ccn 47 + trackNumber

if output > 0
  set prevOutput output 
  set output 0
	# https://www.circularlabs.com/doc/v2/scripts.htm#MidiOut
	MidiOut control 15 ccn 127
else
  set output prevOutput 
	MidiOut control 15 ccn 0
endif

The Mute/Unmute functionality works, but the LED doesn't get lit.
I have these devices configured as MIDI Output devices:

IAC Driver Bus 1
nanoKONTROL2 CTRL
Morningstar MC8 Port 1

I checked with Midi Monitor and weirdly, the right cc are only sent to Morningstar MC8 but not the other two. When I remove the Morningstar MC8 from the MIDI output devices configuration, the LED light control works and MIDI Monitor shows that cc messages are sent to nanoKONTROL2 (but not IAC). So I can't have multiple hardware devices configured as Midi Output devices?