We have a Winforms chart (with a custom axis) that displays correctly in build 15.8.25.12 but which does not display at all in build 18.4.26.12. The chart sits within a tab control and when switching to the tab containing the chart, the UI does not refresh in area where the chart is located. I have saved the chart control state to file to make a comparison, and apart for some information about UniqueId, there does not seem to be any significant differences. When I was trying to debug the problem inside of Visual Studio I tracked a problem down to the method BuildAxisGroups inside of Nevron.Chart.dll, the method was returning a null value (due to an NAxis object being null from an element not being found from the GetElementFromUniqueId method).

A separate issue that I found while trying to get to the bottom of this problem is, when trying to display the editor dialog for an NDocument, there was that a null reference exception was being thrown. I tracked this down to a call to IsDisplayedOnAxis within the method UpdateAxesPageFromSeries on the class NSeriesEditorUC.

I have uploded the chart state in both versions of Nevron chart.