Microsoft Office comments in doc and docx files refer to a range of text with a starting and an end point. Writer only attaches the comment to a single point in the text. This creates inter-operability problems - the Microsoft solution is clearly superior and the information in a doc / docx file is lost when opened or saved in libreoffice.
This may require upgrading the odt specification.
This longstanding OOo bug has been neglected by Sun/Oracle for 7 years! Time to fix this, it would really make a world of difference for professional writers.
*** This bug has been marked as a duplicate of bug 38244 ***