Because a double slash ("//") is used as a literal identifier. Everything after it will be literal text, no tags, no commands, etc... This is not a bug at all...
If you want to use commands, you must only write 1 slash in front. eg:
/me (!IP)
and not
//me (!P)
Also see
http://www.msgplus.net/help_cmdtag.php and the "/text" command.