I made a test which you can see in the attached movie and I was able to reproduce that in some scenarios the Apply Class does not work as expected. You can see in the video that the class is properly applied to the UL tag, but not to the DIV tag.
I logged this unexpected behavior issue in our bug tracking system and we will do our best to fix it in the Q3 version of RadEditor. I also updated your Telerik points for your bug report.
the Telerik team
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