@Optimus
When you use 100% sparse infill density you have to select sparse infill pattern - Rectilinear. The slice should then fill the gap accordingly, but it is not.
I have attached two views (same model) showing that the one is missing the sparse infill. The other when changed to 98% Gyroid is working ok.
This has to be a bug as at present there is a gap in the rendering and the physical print. You will also not that the filament used and print time are different. 
Cheers
