I have SQL look up object that find list of names in a sql database and that works fine. I want this field to be required but I found a bug where a user can pick a name and then go back and pick default blank user. It will by pass validation on the field and I added validation in the rules and both of them didn't work making the field required.
Sql Lookup tool and Making it required field
+3
+15- Nintex Partner
Are you able to show the settings for your look-up?
I'm wondering if the blank is being picked up from your SQL list, or if the blank is input as a default by Nintex. If the latter, I think there's a custom text field there, so then you could instead say "if NotEquals{Self}" -- and if it's coming from SQL, maybe you can exclude it somehow, if the isNullorEmpty isn't picking it up?
Just thoughts for now 
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