In the table on the right,
each row represents a single
property search expression.
The property drop down lists
an aggregate of all of the
properties for all of the types
you selected.
The matching expression is either
a simple string or a regular
expression matching the property's
value you seek within object
types selected.
When you have selected multiple
object types, entering an expression
for a property unique to only a
single type of object will inevitably
lead the search to respond only
with objects having that property
where that property matches the
provided expression.