Is there a limit to the number of lines that can be on a chart? It seems that after 8 RadzenLineSeries that they no longer display. The Series names are in the legend but the colors for all items beyond 8 are black.
Indeed Radzen provides colors only for 8 series. You will need to set custom color for the ones above that count. Use the Stroke property to do that.
<RadzenLineSeries Stroke="#aabbcc" />