Problem importing HTML file

Dear,

While importing a HTML file I encounter problems with an INS tag

Source=

Ongoing pregnancy of the victim should <ins datetime="2015-06-11T14:41:20" cite="martti">always</ins> be ruled out with a pregnancy test.

 

The text is cut into several segments and 'always' is not displayed

However the INS is a standard HTML tag.

How can this be resolved?

Many thanks,

 

Tom