I have each document has an array of strings named datavalues.
For example I have :

{ "_id" : ObjectId("58add926609495b90dc13ea2"), , "datavalue" : [ " _value: ", "A _value: 8", "B _value: 5", "C _value: 2", "D _value:4" ]}

When we search for "datavaues grater than 6 and starts with A " with an aggregation pipeline which contains $match and $project it returns all the datavalues.

I changed the pipeline to : $match , $project , $match , $project => it works !!

when I add another condition "documents contains datavaue grater than 6 and starts with A and datavalue contains B" => it returns all documents .