Are you using a tab container?
I've seen this issue when charts are on tabs. If a chart is on a tab which is not visible, then it is often rendered at the wrong size, and appears that way when the tab is shown
Thank you, that make sense and we have the chart on Conditional Visibility.
I will change from two Chart that's flip to One chart modify MF so insted that will make a better solution and proably take away a problem as well.
I think this Community is great for a New at Mendixperson like me, a lots of helpful people out there=)