Spurious folder cannot be deleted on Windows 11: error 0x80004005

I have a spurious folder on a drive that refuses to be deleted (Windows 11 Pro 25H2, all current Windows Updates installed). I have tried everything, and it's still there.

It started when I tried to create a compressed archive using 7-Zip. The archive was to be created in the parent folder of where the files were; so, I added the ..\ prefix to the file name in the 7-Zip dialog window, but I must have inadvertently typed it at the wrong place, with the prefix in the middle of the file name. So, I ended up with a subfolder called R.. (notice the two dots) in the folder where the original files were.

This folder is empty and shows nothing unusual in the "Properties", but when I try to delete it, I get this error message (my Windows is not in English, so I'm translating, and the original English message may be a little different):

An unexpected error is preventing you from deleting this folder. If you continue getting this error, you can use the error code to search for help with this issue.

Error 0x80004005: Unspecified error

As the description implies, this error code is generic and useless. I have searched it, and found a lot of totally different and unrelated issues, but none remotely similar to mine. The same error occurs when I try to delete the parent folder. I can "Try Again" (which only shows the same error message again forever) or cancel.

The folder is on a secondary data SSD (not the system drive), formatted in NTFS and encrypted with BitLocker (like all my drives, by contractual demand from my clients). I have run chkdsk /f unmounting the drive (which the command required), and it found no errors. I have also scheduled a boot-time chkdsk of the drive, but although the countdown appeared, the check itself never happened, and Windows booted right away. Very strange!

Since I suspect that the issue may have something to do with the two dots in the name, I have also tried to rename it. WIndows first shows me the usual warning when you try to change a file extension. After I confirm, it shows the following message (again, a translation):

It was not possible to locate this item.

It is no longer located in [parent_folder_path]. Check the item location and try again.

I took full ownership of the parent folder with total control to all subfolders and explicitly replaced the permissions in all of them. It didn't work. I tried erasing both the rogue folder and its parent folder with a secure-erase utility, and it didn't delete them either.

Other than this stubborn immortal folder, the drive is working normally. I can even create a new folder in the same parent folder as the rogue one, and then I can delete it normally.

What else can I do? Thank you very much for any help.