The search field in jqGrid doesn’t return the date: 20-03-2020

Question

The search field in jqGrid doesn’t return the date 20-03-2020. For other dates it's OK, but this date is not being returned. Why?

{
  colModel:[{ 
    name:'data_reg', 
    index:'data_reg', 
    align:"center",
    editable:false, 
    formatter:'date',
    formatoptions:{newformat:'d-m-Y'},
    width:10
  }]
}