In order to more easily determine the failure point for your goal, it would be useful for you to post your LightBurn file as an attachment. If the entire workspace is confidential material, create a duplicate of your original, then delete all except this portion and post that.
My first guess would be that your shapes are not closed. Use the feature to select open shapes set to fill, but first consider that you are using two different colors, which implies different settings. For a proper fill, all three should be the same layer.
The top right is the corner of the file you posted, no internal circle. The top left is a circle I added and set to the same layer as the rest of the file.
The only thing I did was to add the circle eyeball-centered in the corner, then changed it to match the fill layer. If I had selected layer 7 before creating the circle, it would have been just that one step.
Your original picture shows a black circle in the center that is not in the file you attached. If you still have that file containing the black circle, select it and change the layer assignment.