Note that the particular category of "missing" matter is "hot intergalactic gas", not dark matter.
Yeah, the last article linked about this topic was less clear. This article is less confusing and makes it clear that they are talking about the 1/3 missing normal matter.
Darn
"Over one-third of the ‘normal’ matter in the local Universe – the visible stuff making up stars, planets, galaxies, life – is missing"