Esearch not pulling all records in for search

I have a parcel viewer located at: http://gis.crookcounty.wy.gov/parcelViewer/ I recently noticed that when I am searching by any of the "Parcel" fields it isn't pulling in all the unique values. I have 5916 unique parcel records but the tool is only showing 2700 unique records. If I go all the way down my list and select "all" it will select all the parcels, but it won't let me search for roughly half of my records by attribute. I have two other layers that I search by "Addresses" and "Subdivisions" that populate correctly.

Any ideas as to what could be causing this issues would be GREATLY appreciated.

Thank you,

Max Masters
Geographic Innovations