Hard edge eraser not completely erasing pixels

[Greybear]

I've set the eraser tool's hardness and force to 100 with a hard edge ticked, and still the tool leaves som shades when I try to erase, and force me to click twice to get rid of all traces of the pixels... What am I doing wrong? Using GIMP 2.10.8

[akovia]

The eraser tool's Opacity is set at 90%.