The issue is caused by something external to Opus locking the files so they cannot be replaced.
We aren't sure what yet, but so far one person has indicated it may be thr OS itself or something low level like antivirus.
There is more information here, as well as some tests that can be run to see if the locking process is the same on your system:
That post and the two after it.
It's probably best to continue in that thread, so the information stays in one place.