I wonder if there’s something peculiar about that specific font? I don’t see it happening on every typeface.
If you drag the Character palette open a little further, you’ll see a control that lets you set the compositing order for the fills and strokes. The default is “Stroke over fill.” If you change the Fill color from transparent to black, set it for “Fill over stroke,” and double the stroke width.
You could use an Add or Screen blend mode to knock the black out of the text, leaving only the white outline, or you could use an Unmult effect.