I tested the described scenario, but the Content property of RadEditor returns all html tags on my side. Can you provide a little more details on the exact configuration you have? Can you send us a runnable sample page where the issue can be reproduced so we can examine it further on our side?
Can you also verify that you are using the latest version of the controls? - 2016.3.914
Telerik by Progress
Check out the new UI for ASP.NET Core
, the most complete UI suite for ASP.NET Core development on the market, with 60+ tried-and-tested widgets, based on Kendo UI.