Adobe Acrobat DC 'add note to replace text' comments not showing

Hi,

I'm working on a PDF file where the my colleague has use the 'Add note to replace text' option (which appears as a strikethrough with a pop-up note) to add comments in certain places. However, when I open the file in both Acrobat and Reader, I can only see the strikethrough line, not the pop-up.

This is a PDF with text, not a scanned document.

The first screenshot is how I can see the file.

The second screenshot is of the original file, from my colleague's system.

As you can see the '200' is not showing on my system.

Please help!