In short, that happens when a member registers and then posts to the forums before his/her registration is fully processed. It's happening more and more lately due to the social login (Facebook/Yahoo/Google) option, which increases the delay. However, we can still lock, delete, ban, etc. as usual, and a workaround to display the username should be coming in the near future.
John
I'm seeing a lot of questions in different forums by "Anonymous". Another glitch?

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