Directory OPUS is a file manager with a feature to preview in a separate pane files that are selected in the file listing pane. This includes images, pdf files, text files and Office files.
The problem with Office files is that they are not shown in the Preview pane if ReHIPS is in any mode other than disabled. As soon as I set ReHIPS to disabled, the Office files are immediately viewed in the preview pane. If I re-enable ReHIPS the problem appears to be gone, but it comes back if I log out and log in to Windows and repeat the exercise of viewing Office files in the preview pane.
What may be worth mentioning is that when I disable ReHIPS and try to preview a Word document (actually it is a LibreOffice document with an odt extension) a dialog comes up saying "Microsoft Word isn't your default program for viewing and editing documents. Do you want to select the file types that Word should open?".
If I respond with No, then the previews load properly. If I respond with Yes then I'm taken to Windows settings to define which program should open Word documents etc. Even if I make no changes in Windows settings, the previewer in Directory OPUS then works as I describe above. Strangely, this also fixes Excel document previews, but again it's a temporary thing. Moreover, no dialog ever comes up about Excel, but only about Word.
EDIT: This is an interesting thread: https://resource.dopus.com/t/activex-preview-office-web/5472/5
Please note that Windows File Explorer with preview enabled does not show previous of Office documents and in fact exhibits a similar behavior to what I had experienced. I don't know if this may help the ReHIPS developers discover what it is with ReHIPS that causes this problem.