If you install Directory Opus 13.5.4 (Beta) (or later, if appropriate at the time you read this), does the problem still happen with that?
Unfortunately, I haven't been able to reproduce the issue so far, but it could be something we've already fixed in the newer betas.
It may also be worth checking what happens if you do the same thing in File Explorer, in case the issue is with Microsoft's custom handler for the Assembly folder.