Does it work in File Explorer's viewer pane?
If it also doesn't work in Explorer, the issue is with Word/Office rather than Opus, and you may need to ask Microsoft for support if none of the suggestions here get it working again.
My advice with Word is usually to try reinstalling it, which often fixes things. Check what the preview handler list in the ActiveX + Preview + Office + Web plugin shows as well (some screenshots are earlier in this thread).
Opus 12.9 is here. "New versions are made available several days before they will be detected by the update checker. You can download Opus using the links below if you don't want to wait."