Forums Bug Reports Highlight.

I actually noticed this on 6.12 but forgot to post it, still present in 6.14.
Highlight doesn't highlight (in /echo) if the matching word is the first word.
//echo -ls $highlight(1) - | echo -ls - $highlight(1)
^^ Assumes $highlight(1) is not an $identifier|%variable.

You would need to ensure that the highlight item itself has the "Nickname and Message" match option enabled. If it isn't enabled, the first word in the line is assumed to be a nickname and is not used during the match.