Plugins with element criteria selection does not work for empty or zero values
When you do this:



$criteria-&gt;accent = '';


Craft is going to look for users where the accent field’s DB cell is an empty string.

Those values are probably null though, if they aren’t getting returned.

Try setting your accent param to :empty: instead of ''. When you do that, Craft will search for both empty strings and null values, so you should get the results you’re expecting.