I am trying to display custom XAxis labels. If I leave this line without passing the values it shows correctly

AxisMarks() { value in

but when I update to this to the following it doesn't display anything on the xAxis, although model.xAxisLabels is correct, and even if I replace with another array it also doesn't display.

AxisMarks(values: model.xAxisLabels) { value in

Chart {
   ForEach(model.items) { item in
      BarMark(
         x: .value("Time", item.period.identifier),
         y: .value("Distance", item.distance)
      )
   }
 }  
 .chartXAxis {
    AxisMarks(values: model.xAxisLabels) { value in
        AxisValueLabel {
          if let stringValue = value.as(String.self) {
             Text(stringValue)
          }
        }
     }
 }

If I print stringValue I see the following:

AxisValue(_value: Charts.AnyPrimitivePlottable.category("J"), _index: 0, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("F"), _index: 1, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("M"), _index: 2, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("A"), _index: 3, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("M"), _index: 4, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("J"), _index: 5, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("J"), _index: 6, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("A"), _index: 7, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("S"), _index: 8, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("O"), _index: 9, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("N"), _index: 10, _count: 12)
AxisValue(_value: Charts.AnyPrimitivePlottable.category("D"), _index: 11, _count: 12)

Can anyone see what i am doing incorrectly?