Enhanced Search Dropdown list doesn't populate

OK, I have looked at this and looked at this... can you tell me any reason that this dropdown list (eSearch 3.5) won't populate?..no errors, it just doesn't pull in any values. it is a joined layer. Here is the rest end point field description:

Layer: Building (ID: 0)
FACLIB.FAC$OWN.structure_existing_area.Location ( type: esriFieldTypeString , alias: Location , length: 50 )

Here is the expression:
<expression alias="Location" textsearchlabel="Search by Location">
<values>
<value prompt="Choose from dropdown list:" uniquevalsfromfield="FACLIB.FAC$OWN.structure_existing_area.Location" isvaluerequired="false" >upper(FACLIB.FAC$OWN.structure_existing_area.Location) LIKE upper('%[value]%')</value>
</values>
</expression>

If I use a userlist, the list and search task work fine. Is the dropdown list creation unable to process this "join layer" field name or something? or could it be a limitation in the number of features from which it is able to process unique values?