SOLVED.
Forced PCRE to use utf8 check. Also got rid of the space requirement after the colon since that was messing up some people too.
Subs-portal.php, line 1278 started with
if (preg_match('~^@(.+?):~ ' . ($context['utf8'] ? 'u' : ''), $shout['text'], $target)
Now if (preg_match('~^@(.+?):~u', $shout['text'], $target)