max() does not return negative Double

[dmtch-github]

Hello
My JSON

{
  "idTitle": "26a",
  "amount": -719.92
}

I want get 'amount' as Double, when 'idTitle' == '26a'

My Path Expression
$.max($.[?(@.idTitle == '26a')].amount)

Expected result
-719.92

Real result
5e-324

Why jsonPath return wrong result?
How may I get single Double value (not List)?

Java, com.jayway.jsonpath version 2.8.0

Thanx