Windows file manager not DirOpus suddenly opens path link

Since installing DirOpus 10 years ago, DO always opened path links.
That changed yesterday. Windows file manager window now open path links instead of Dir Opus.
How to revert to DirOpus?

Specific example: Adobe Acrobat pdf document is open
click File, click Properties
click Properties
at Location: click path
DirOpus file manager opened link until yesterday.

Try turning off Explorer Replacement in Preferences / Launching Opus. Click Apply, then wait 15 seconds. Turn it back on and do the same.

That should repair the registry settings, which may have been modified by something else.

Thank you. Tried your remedy yesterday before requesting help, but did not wait 15 seconds.
Tried today waiting more than 15 seconds. Selected Replace system folders first. No change
Selected all folders. No change
Rebooted. Tried again. No change.
Explorer, not DirOpus opens link.
As noted, this change has never happened since using DirOpus for more than a decade.

Does it only affect that particular button within your PDF viewer?

What happens if you create a folder on the Windows desktop and double-click it, for example?

Just created folder on desktop.
Clicked. DirOpus opened the folder.
Have several existing folder shortcuts on desktop.
DirOpus opens those via shortcut.
I use pdf numerous times daily, clicking Location to then copy path with DO button (A clipboard icon).
I use DO dozens of times daily for various tasks.
DO executes all tasks as usual, but for pdf location issue.
Will be glad to perform any experiments you suggest.
Thank you

Could you post a screenshot of exactly what you're clicking on with the PDF files?

Is it part of Windows, or part of a PDF viewer/editor or similar tool?

2 jpg pdf clicks 1%20DirOpus%20pdf

If other methods of opening folders still route to Opus, it's possible that whatever tool is shown in the screenshots has changed the way it launches folders. If that tool was recently updated, it may now be using a method that explicitly asks for Explorer to open the folder rather than asking for the default file manager.

No Adobe Acrobate updates. Only recent updates are Win7.
Yesterday wondered if reinstalling DO might resolve the issue.
Will try. First backup DO settings, presuming DO settings are not the issue because no changes in DO for a long time.

Reinstalling DO restored DO preference for opening pdf document Location.
All settings seem same so no need to restore settings backup.
Are settings "transferred" when upgrading version?
Thank you for your suggestions

Settings only get cleared if you uninstall (or in very rare/exceptional cases where we reset specific individual settings on new versions, e.g. font sizes when high DPI support was introduced).