There are a couple strange things here.
- You are using 0.8.07. That is an ancient release of LightBurn.
- Your speed is set to 1500 mm/sec - you likely meant to use 1500 mm/minute
For photos, if they are dithered, there are only two S values - 0% and 80% power (you asked for the 80). The laser power is toggled off and on to create dots, and the spacing between them is adjusted to make shading. This is normal. You are likely expecting varying S values, which you would get using the Grayscale image mode instead of one of the dithering modes.