Hi,
Generally, we do not recommend working directly with the visual elements in RadGridView as it is a virtualized control and its elements are reused as they are brought in and out the view area. You can check our online documentation explaining how the UI virtualization works.
May I ask you to share some more details on how do you set the Background of the cells in code behind? What is the result if you disable freezing the columns at all?
Regards,
Dimitrina
Telerik
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