RadGridView is a virtualized control and all it visual elements are recycled and reused on scrolling. So, you need to keep that in mind when trying to set a property like background, foreground, etc. of its cells for example as it will be either lost or applied to another cell.
My recommendation would be to keep the logic on a data level and work with CellStyleSelector for instance. You can expose a new property containing the information which style should be applied and update it on calling the methods you want.
You can run through our online documentation and demos for a reference.
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