windows latest update Ver: 1809, os Build 17763.292, 64bit.
Seems to stop Dopus 12.12 x64 .as the default explorer, and opens win Explorer.
It's working OK here in 1809.
Is Explorer Replacement still turned on for you in Preferences?
If it's on but not working, try turning it off, applying that, then turning it on and applying again. That will re-write the registry settings it depends on.
If that still doesn't work, try reinstalling Opus by running the latest installer over your existing installation. (No need to uninstall, which would wipe your config.)
Thanks Leo, That worked.
Once again Thank You
oldmanemu2