CSS classes removed in module fields of type Long text with

Hi All, 

We are facing a strange issue when populating the content in the module field of type Long text with rich text editor.

We populate the content with HTML markup and css applied to HTML tags and save the content. 

CSS applied to HTML tags not work.

We open  the content in Edit to verify either CSS available in markup or not, we are surpised, Sitefinity removed all the CSS aplied to HTML tags in the content.

We  made a short video to elaborate the issue.

www.screencast.com/.../VPDYEGvD

Anyone can help to fix the issue.

This drove me crazy today. 

knowledgebase.progress.com/.../Shared-Content-Block-and-Long-Text-Field-filters-HTML-even-after-setting-RadEditor-filters-to-None