Problems with strange gradations and boundaries appearing in the illuminance distribution map

I am trying to create an illuminance distribution map for a specific date and time using Ladybug Tools 1.6.0.
The analysis results show strange illuminance gradations and boundaries in one room with no partition walls.

I have reviewed the settings of each component in Grasshopper, and there are no problems with Material settings.
The error does not seem to be caused by such detailed simulation settings.
If you have ever had a similar strange illuminance distribution map, please let me know how you solved it.
For reference, I have saved the 3dm and gh files I created in the following shared folder, so please check them if necessary.

Thanks for your help.

I suggest you check the data structure of the sensor grid, at some point it doesn’t match in the order it is supposed to, but can be messed up.