In general there can be 2 reasons:
1) something is changed outside Sonar. From your second screen shot it is unclear either your MCU is connected to the computer with USB or throw some MIDI interface. In both cases there is normally some way (f.e. hardware LEDs) to check that some communication ongoing
2) configuration is corrupted inside Sonar. Check Control Surface preferences either Input/Output for MackieControl plug-ins are still correct. Next attempt can be removing it from the configuration and reinserting. When still no luck, configuration files can be removed (Sonar will regenerate them).
You can also check either communication is broken in one direction only or completely, remove Control Surface configuration and try to record MIDI track with MCU as an input.
