Your images clearly show the issue, but I am afraid I cannot provide a workaround for the moment. Please, accept our apologies for the inconvenience.
In addition I would like to point you to our new RadHtmlChart
. While it does not match the features of RadChart yet, it takes a different approach, you can find more details in this article:
RadHtmlChart vs RadChart - Which ASP.NET AJAX Control to use for my project?
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed