Delete all posts by this user feature doesn't work

[crazlunatic]

Hi. Someone has spammed my forums. I checked their post, selected delete posts as spam in the menu, then checked the delete posts and threads affected by this user. I'm assuming this featuer is supposed to erase all posts and threads the user has started. But upon checking this box, it does nothing other than delete the selected post.

How can I fix this? Thanks

Edit: Never mind, for some reason all his messages are gone a minute later. I guess there's a delay