I apologize for the inconvenince, but I was not able to reproduce the problem.
Could you please send us the content of the RadEditor that you are trying to save. This will be of help in order to reproduce the problem on our side. In addition please send us the respective ConfigFile.xml, ListConfigFile.xml, ToolsFile.xml, ListToolsFile.xml files located in the Program Files\Common Files\Microsoft Shared\web server extensions\wpresources\RadEditorSharePoint\220.127.116.11__1f131a624888eeed\Resources folder (18.104.22.168__1f131a624888eeed depends on the version of the control).
the Telerik team