I traced it through. Somehow, AutoRepaint was changed to false once it was viewed. I guess it could also have happened in design time. Setting AutoRepaint = true resolved the problem.

I have a several TCharts (6.01) with two line series. All reside on individual tabsheets. They have been working fine for the past few months, and just started to misbehave. 1) Everything is ok as long as the tab sheet is not displayed. When it is displayed, the chart stops updating, even though new...