It looks like the mannequin doesn't work server side, but the client shows it working until a refresh from the server.
I'll go ahead and add this to the bug tracker, but if you find more bugs and confirm how to replicate them, you can post them on the bug tracker (click Bugs at the top)
yourself. But if you really don't want to, you could still make a post on the forum, we rather get a report than no report at all.
Thanks for the report.