Problem is Spline and Spline Area charts show data where data values are zero

using version Version : 18.2.20182.175 

I have verified this with the ChartTypes sample program and assigning a different Data class configured like so: 

public class DateUse
{
 public string Date { get; set; }
 public double Nuclear { get; set; }
 public double Coal { get; set; } 
 public double Oil { get; set; }
 public double Gas { get; set; }
 public double Hydro { get; set; }
 public double Renewable { get; set; }
 public double NonRenewable { get; set; }

}
class EnergyUseByDate : ObservableCollection<DateUse>
{
public EnergyUseByDate()
{
this.Add(new DateUse() { Date = "Jan", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });
this.Add(new DateUse() { Date = "Feb", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });
this.Add(new DateUse() { Date = "Mar", Nuclear = 475, Coal = 550, Oil = 200, Gas = 250, Hydro = 425, Renewable = 425, NonRenewable = 1475 });
this.Add(new DateUse() { Date = "Apr", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });
this.Add(new DateUse() { Date = "May", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });
this.Add(new DateUse() { Date = "Jun", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });
this.Add(new DateUse() { Date = "Jul", Nuclear = 0, Coal = 0, Oil = 0, Gas = 0, Hydro = 0, Renewable = 0, NonRenewable = 0 });

}
}

The Spline and Spline area shows a clear "bump" for all types in May and June  also the hover tip shows the data = 0