With the new 1.0.3 version, I see some users listed as their member_id. I searched on the database, and these users don't exist. So, I guess, this is the new behavior for what, in the past, the app showed "Guest".
My best guest is that the app is logging users who are trying to register but don't finish their registration process, so the app ends up linking to non-existing users. As you know, IPS deletes incomplete registration attempts after 24 hours.
I believe this issue could be easily solved by adding a cronjob that deletes these records that point to non-existing users.