Endnote 7.7.1 issues on MacOS Sierra

I came up recently against highlighting and underlining issues using the Endnote 7.7.1 on a MacOs Sierra.

The problem appears when I highlight or underline a PDF file. 

More precisely the lines I choose to highlight or underline are shown upside down.

Does anyone knows what may cause this problem?

In the attachment you can see a printscreen.

Thank you in advance!