I am adding comments to documents but it always lists “Author unknown.”
Never use the old, obsolete and foreign binary .doc file format. Note: there is not (never was and never will be) 100% compatibility between the different file formats. You always will lose some formatting properties (or even contents!) from your important documents, when you save them into foreign file formats.
Just a tip:
Try to fill your personal data in the settings of the LibreOffice.
A Word question!
If the author of the Word document sets it to remove all personal information then all comments from other people subsequently will be “unknown author” as there will be no identifying info.
It can also happen if you haven’t entered a name in Tools > Options > LibreOffice > General