Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Pretty straightforward, its what the title says.
Screenshot (courtesy of KronoS, who first noticed something was wrong):
The ping works in that the notification shows up, as well as the sound, but the name is not highlighted.
This was caused by this rather huge change to chat's handling of @replies. Fixed now, thanks for the report.