We're not aware of Microsoft/Windows causing any issues like that recently.
If Explorer Replacement isn't working, you can sometimes fix it by selecting "Don't replace Explorer", clicking Apply, then going back to the recommended setting and clicking Apply again. (This makes Opus re-write the relevant registry settings.)
Another thing to check is that none of the Windows Compatibility Settings have been turned on for Opus. (If Opus thinks it's running on an older version of Windows then it might use Explorer Replacement methods which don't work on newer Windows versions.)