Grid lines intervals for stacked bar chart

We are using Kendo 2014.3.  We have a stacked bar chart which is working fine, with the value axis along the bottom.  We would like to be able to set the grid lines to a different interval, which should be possible now using the Step method.  However, when I try to set Step for any of the value axis elements, it causes that element to disappear.

Here's a slightly simplified version of the Razor view I'm using:

    @(Html.Kendo().Chart<ProjectChartDataPoint>()
          .Name("ProjectChart")
          .SeriesDefaults(z => z.Bar().Stack(true).Gap(0.5))
          .Series(series =>
          {
              foreach (var color in Model.Colors)
              {
                  ProjectChartColor color1 = color;
                  series.Bar(Model.DataPoints.Select(p => p.ColorPoints[color1])).Color(color1.toString());
              }
          })
          .CategoryAxis(axis => axis.Categories(Model.DataPoints.Select(p => p.Name)))
          .ValueAxis(vaxis =>
              vaxis
                .Numeric()
                .Title("% of budget")
                //.Labels(labels => labels.Step(20).Visible(true))
                //.MajorTicks(ticks => ticks.Step(20).Visible(true))
                //.MajorGridLines(major => major.Step(20).Visible(true))
                //.MinorTicks(ticks => ticks.Step(10).Visible(true))
                //.MinorGridLines(minor => minor.Step(10).Visible(true))
           )
          )

If I uncomment the MajorGridLines line, or any of the others in the value axis, then instead of the interval changing, the grid lines or ticks or whatever disappear entirely.  We have a line chart where this is working fine.