There are two ways to change the back color of our controls - one is to change the BackColor
property of the control, or reach the FillPrimitive
through the Smart Tag -> Edit UI Elements and customize it. We tried to reproduce the reported issue both ways but the control worked correctly. Can you, please, give us a more detailed description on how to reproduce the issue, or send us a project that shows the problem?
All the best,
the Telerik team