Clipboard won’t keep pre tags

Hello everybody,

As you know, copied text in editor retains their html tags so you don’t need to format them again. However, clipboard does not save pre tags. I am using a plugin called crayon syntax highlighter for publishing codes. I am sure the text was once copied and pasted with format. The interesting thing is that format is preserved in any tag other than pre tags. Does anyone have any idea which can give me a hint to solve this problem?

Thanks.