Heading 2 formatting issue in ZenDesk Editor

Hi to Community!       

Yesterday I discovered strange bug in ZenDesk Helper editor which have not seen before.

After creation of an article I have discovered incomprehensible random sections throughout the article text.
In the editor, indeed, it is defined as heading 2 - the format that determines how the text gets into the navigation as section.

But in the text of the document itself (document from where I copy text itself), the formatting is different - normal text, which is usually (and everytime before) defined in the editor as paragraph, plain text.

Maybe someone stumbled upon same issue and have a suggestion?