I have a situation where some folders and/or files cannot be deleted because "This is no longer located in [drive letter]:. Verify the item's location and try again." This doesn't appear to be Opus' fault as I can rename the file/folder, and move it as well. Opus displays the entire folder and file tree involved and properties gives the correct number of folders and files and the correct size as well. This occurs only occasionally in both windows 10 64-bit and 7 64-bit befor it. Same thing happens if I try to delete in safe mode.
Deleting without using the Recycle Bin may work. Usually you can do that by holding shift when you click delete. (You can also change the default under Preferences / File Operations / Deleting Files.)
The Windows Recycle Bin has some bugs which can be triggered by file/folder names of particular lengths, and possibly other things. If that's what is happening, bypassing it can avoid the bugs.
Since it is a Windows error and not specific to Opus, searching for the error message may find more suggestions and possible explanations. I found a few doing that, but don't know which may apply to your situation.
I had the same problem. I could add folders to it, rename the sub-folders, copy it, but any new folder that I added I could not delete! The program could not find it to delete it but knew where it was to copy or rename.
By doing what leo suggested (shift delete) an un-protect advisory opened. I had checked earlier to see if it was protected, and I thought it was not protected, but I could have been wrong. Well shift-delete did delete it and all of the the sub-contents.