I exported some stems from busses from a sonar project into MB for testing/learning.
 
The radio select buttons on each track to send/assign the output to a mixbus do not illuminate or change color but do route the sound so its difficult to verify the output by a visual feedback.
 
I inserted a stereo fx into a mixbus (uad Fatso) but it appears only the left channel is receiving audio

Ham N Egz
 
The radio select buttons on each track to send/assign the output to a mixbus do not illuminate or change color but do route the sound so its difficult to verify the output by a visual feedback.
 

Works here. Maybe it has to with your scaling? Try other scaling just to see if they get illuminated.

Ham N Egz
 
I inserted a stereo fx into a mixbus (uad Fatso) but it appears only the left channel is receiving audio

This is another "wonky" thing about MB that SONAR just automatically takes care of.
 
Not at the DAW right now but it might have to have the plug's pin assignment set.

Cra$h Dawg,
 
Mixbus Pin assignments.
 
It's for MB3/4 but I'm sure it's the same in 32C.