I have a grid binded in a panel and the panel is not visible. On postback, the panel is then set to visible and the grid no longer has the default layout when displayed.
Please upgrade the controls to the latest version and see how the behavior changes. The current version is 2015.1.401.
In case the behavior persists please elaborate in more details on what is your scenario. Is the issue observed in all browsers? When are you changing the Visible property of the Panel control? What is the incorrect appearance? Please send a screenshot or a video of the issue.