Threshold range in Segment Editor includes values outside of range

I’m using Slicer 4.11.20210226 on Windows 11.

I want to create a segmentation of all values greater than zero.

When I set the lower threshold to e.g. 0.2 it still includes pixels with values equal to zero (you can see in the screenshot that I was hovering over a value that is 0 and the entire screen is in green). Only when I set the threshold >= 1 the 0 values disappear.

Is it maybe related to the fact that that the data array of the image is in uint8, so a float threshold doesn’t work?

(why I’m doing this - I want to create a segmentation of the entire volume and this seemed to be the easiest way)