Paint.NET :: Resizing Image Removes Elements?

Whether just dealing w/ a png file (resizing) like attached, or converting to smaller sized icon, for the most part it eliminates the white circle, when reduce to somewhere around 32 x 32 px.
 
Maybe this is because the reduction makes the given element too small to reproduce?
 
But, in the reduced versions, there are PARTS of the white line that are clearly visible - but not a solid white line.  So if it shows part of the line, as an intermittently dashed line, why can't it show the entire line?
 
The image was created  /  saved at 32 bits.  It's not only a problem dealing w/ icons - it's reducing png files as well.
 
I'm thinking it may be better to start off w/ an image close to the finished size.  But w/ icons in one icon file ranging from 16 to 64 & even 256 px, that's hard to do.