@devadrianhankin
My intention was to ask/show you → why using public data, if you also can get all private data instead?
However, when does the slug gets generated? During the registration-process? I think it will be so.
So taking a look onto my own example PMD (public)…
…hmmmmmm… everything seems to be correct → no empty fields inside “SLUG” DB-field.
So, perhaps something works wrong on your registration-process, idk.
BTW: you will find the example-DB shown above here…