smoothed_covering_grid() seems to be doing an unexpected transformation on the data.
See the attached images, one is created using “covering_grid()” and the other with “smoothed_covering_grid()”; that is the only difference. 

This doesn’t make sense to me, but… Here, I’m looking at the data attribute “HII_Density”. I do not have issues with “smoothed_covering_grid()” when I render any other attribute (HI_Density, Metal_Density, Temperature, etc)