Confirmed. I created a document in LibreOffice Writer 3.3.2, added comments, and exported the document with comments. However, when I opened the document in Evince, the comments are greyed out and cannot be read.
I also tested reading the PDF with Acrobat and discovered that the comments were indeed readable. However, when viewed with Preview on a Mac, again the comments are greyed out and illegible.
Confirmed. I created a document in LibreOffice Writer 3.3.2, added comments, and exported the document with comments. However, when I opened the document in Evince, the comments are greyed out and cannot be read.
I also tested reading the PDF with Acrobat and discovered that the comments were indeed readable. However, when viewed with Preview on a Mac, again the comments are greyed out and illegible.