In the standard inventory field on the item card the date filter is not in play. So that field can not be used for showing inventory at a particular date. The net change field might be an option. That field takes in to the calculation the date filter.
Here you can see the calculation for the inventory field.
field(68; Inventory; Decimal)
{
CalcFormula = Sum("Item Ledger Entry".Quantity WHERE("Item No." = FIELD("No."),
"Global Dimension 1 Code" = FIELD("Global Dimension 1 Filter"),
"Global Dimension 2 Code" = FIELD("Global Dimension 2 Filter"),
"Location Code" = FIELD("Location Filter"),
"Drop Shipment" = FIELD("Drop Shipment Filter"),
"Variant Code" = FIELD("Variant Filter"),
"Lot No." = FIELD("Lot No. Filter"),
"Serial No." = FIELD("Serial No. Filter"),
"Unit of Measure Code" = FIELD("Unit of Measure Filter"),
"Package No." = FIELD("Package No. Filter")));
field(70; "Net Change"; Decimal)
{
CalcFormula = Sum("Item Ledger Entry".Quantity WHERE("Item No." = FIELD("No."),
"Global Dimension 1 Code" = FIELD("Global Dimension 1 Filter"),
"Global Dimension 2 Code" = FIELD("Global Dimension 2 Filter"),
"Location Code" = FIELD("Location Filter"),
"Drop Shipment" = FIELD("Drop Shipment Filter"),
"Posting Date" = FIELD("Date Filter"),
"Variant Code" = FIELD("Variant Filter"),
"Lot No." = FIELD("Lot No. Filter"),
"Serial No." = FIELD("Serial No. Filter"),
"Unit of Measure Code" = FIELD("Unit of Measure Filter"),
"Package No." = FIELD("Package No. Filter")));
Caption = 'Net Change';
DecimalPlaces = 0 : 5;
Editable = false;
FieldClass = FlowField;