Previews show for all files except LibreOffice and Word documents.
On my paintings, Windows Explorer can show preview of Microsoft Office documents the use of Windows Explorer’s preview panel (View > Press “preview panel” icon and pick a Microsoft Office report). That laptop has Microsoft Office 2010 and Windows 10, 10240 update.
But on my laptop I even have Windows 10, 10586.63 update with LibreOffice four.4.Five.2, and I can’t preview .DOC or .XLS documents, nor .ODT or .ODS documents on Windows Explorer’s preview panel.
Do you mean that you can leaf through the document, or that you only see a thumbnail image of the first page? Please note that MS Word is developed by Microsoft and that, therefore, it’s easy for MS to add previewing of their own file types in Windows Explorer. LibreOffice is a competitor, and why would MS help the competition?