Laser power control using Mach 3 Light burn vs Inkscape

I have been using LightBurn for a few years now to cut wood veneers. It works great for this as I usually run the laser at 100% power. Recently I started an engraving project that requires some different power settings. I am now realizing that I am unable to change the power setting in when I use code generated by LightBurn. I use the GRBL M3 1.1 set up in Lightburn and modify the code with scripts to change M3/M5 to M11Px Sx and M10 Px.

If I generate code with Inkscape I can adjust power easily.

When I compare the M11Px Sx and M10Px code generated by the 2 different program they look identical. But something is preventing the lightburn code from controlling power.

I know LightBurn is not really meant for Mach 3 machines but I have been fairly successful with it…I guess as long as I want it to fire at 100%. But not being able to change the Sx commands is very limiting. I work around this to some degree by changing feed speed but that is also quite limited, the lines get shaky due to vibration when moving very fast on my machine, 3000-4500 mm/min. 1000-2000 looks quite good but I’d still like to be able to control power in LightBurn.

modified light burn code to use M11Px Sx and M10 Px

; GRBL-M11P2 S5 (1.1e or earlier) device profile, user origin
; Bounds: X103.37 Y2308.74 to X125.98 Y2326.4
G00 G17 G40 G21 G54
G0 X0 Y0
; Cut @ 1000 mm/min, 10% power
G0 X-18.811Y17.664
; Layer engraved flakes
M11P2 S5
G1 X-2.185Y-1.319S10F1000
G1 Y-3.21
G1 X-1.612
G1 Y-1.709
G1 X1.612
G1 Y-7.459
G1 Y-0.473

InkScape Laser tools code

;Inkscape Lasertools G-code
;GitHub - ChrisWag91/Inkscape-Lasertools-Plugin: A simple plugin to convert inkscape vector graphics to Gcode for DIY laser engravers

G90 ;Absolute programming
G21 ;Programming in millimeters (mm)
M03 S1 ;Activate laser and set power to 0 (CUSTOM)

; START perimeter strategy
G01 F2000.0
M10 P2
G00 X59.19 Y162.39 F2000.0
M11P2 S5 F2000.0
G01 X58.59 Y162.27 F2000.0
G01 X58.02 Y162.22 F2000.0
G01 X57.24 Y162.34 F2000.0

Does anyone have any ideas?

Perhaps the M3 is required?

I may try using that header in the LightBurn code and see what happens… Thanks for the suggestion.