M42 Command Issues - LED Lighting  

M42 Command Issues - LED Lighting

I have had some issues testing the G Code to implement LED lighting in all my prints, I have been trying to use Pronterface to test the M42 commands to pins to see that they work, but all pins I have used (even ones that others have used in tutorials, see https://blog.prusaprinters.org/how-to-create-beautiful-3d-print-timelapse-videos/ ) nothing happens. I have been trying to use the J19 Pin #7 as per the tutorial I linked (Digital Pin P73) but nothing happens. I have the following feedback from Pronterface after waiting 10 minutes for the command to perform:

Connecting...
start
Printer is now online.
echo: 3.7.2-2363
echo: Last Updated: Jun 27 2019 17:35:17 | Author: (none, default config)
Compiled: Jun 27 2019
echo: Free Memory: 2021 PlannerBufferBytes: 1392
echo:Hardcoded Default Settings Loaded
adc_init
CrashDetect ENABLED!
FSensor ENABLED
echo:SD card ok
echo:busy: processing
echo:Unknown command: "105"(2)
MMU not responding - DISABLED
>>>M42 P73 s255
SENDING:M42 P73 s255

Pronterface does respond to my axis movements when I click to move them back and forth, so the printer is receiving commands from my PC.

Before you ask, I have tested the MOSFETs I set up along with the LED strips installed on my enclosure multiple time, and it all works. Even using the original remote that came with the LEDs works. Touching each color control pin to the 12V + ends on my LED power supply causes the LEDs to light up, so clearly the printer either isnt sending the signal to the LEDs, or isnt getting the command from Pronterface. I dont know which is which, but all pins I have tried (J19 pins 5, 7, 12, 11 and 8) but nothing does the trick. I also flashed the firmware again to the most recent (3.7.2 as of now) and that didnt change anything.

Any idea why this isn't working? Any help would be greatly appreciated!