This bug exists on both sites, on meta and on main.
The word is there, but its text color is in the same as the background (technically, the background on the span is black, but has an opacity of 0, which is making it transparent).
Example: http://meta.askubuntu.com/users/8698/dan?tab=activity&sort=accepts
Though, I suppose the bug is that its background should be #2db651
, but another CSS rule is taking priority and making the background on the word transparent.
This is reproducible on Firefox, Google Chrome and Chromium.
As you can see from the screenshot below, if you try to select the word, it is there.
The following is a screenshot of the span's CSS in Firebug. If I disable the background:rgba(0,0,0,0)
property, the accepted word becomes visible with a green background.