Cannot unlock a folder; weird…

Hello,

I was copying movie files from one disk to another, and, of course, this took some time. In the middle of the copy progress, a dialog told me the destination wasn't writeable; the copy stopped, with half the files copied. Ok, weird…

Then, I went to the destination folder and sure enough, the crossed pencil icon was there (and the authentication dialog showed whenever I wanted to create a new folder or otherwise modify the folder). Other folders, and the root directory don't have this problem; they can be modified as expected.

I tried ejecting (even powering off) the disk; this problem remains.

In the Get Info window of this folder (which is directly on the root directory; no parent folder), neither the “Shared” or “Locked” checkboxes are checked. As for the permissions, I don't recall how they were before, but I have currently set read, write and execute to the owner, group and others users (using the Terminal “normally”, I got “permission denied” messages, but I could change the permissions using sudo; I'm well aware I would certainly be able to delete this folder with sudo as well, but I'd like to understand what's going on).

So, here's the output of “ls -le” for this disk (it's on a french localisation; the offending folder is the one named “Movies”):

ls -le /volumes/nouveau

total 896

-rw-r--r--@ 1 Me staff 69632 1 jan 1970 LaCie 10GB Online.exe

drwxr-xr-x@ 60 Me staff 2040 17 aoû 00:33 1

0: group:everyone deny add_file,delete,add_subdirectory,delete_child,writeattr,writeextattr,chown

drwxr-xr-x 5 Me staff 170 20 mai 18:15 Backup

drwxr-xr-x@ 5 Me staff 170 7 nov 2010 Bin

-rw-r--r--@ 1 Me staff 47104 2 fév 2011 Desktop DB

-rw-r--r--@ 1 Me staff 330946 2 fév 2011 Desktop DF

drwxr-xr-x 4 Me staff 136 16 aoû 23:32 Images, sons et séquences

-rw-r--r--@ 1 Me staff 394 1 jan 1970 LaCie.ini

drwxr-xr-x 5 Me staff 170 17 jul 21:57 MobileSync

drwxrwxrwx@ 6 Me staff 204 17 aoû 02:23 Movies

0: group:everyone deny add_file,delete,add_subdirectory,delete_child,writeattr,writeextattr,chown

1: group:everyone deny delete

drwxr-xr-x@ 8 Me staff 272 20 déc 2016 Scriptes

drwxr-xr-x 32 Me staff 1088 17 aoû 02:39 Séquences

drwxr-xr-x@ 3 Me staff 102 26 jul 2017 System Volume Information

I'm not really a Unix guy, so the additional lines (starting with '0' and '1') are meaningless to me; I just recognise “something” is preventing a lot of things in this folder (what is that “something”?). Still, the permissions are full.

Re-reading the output above, I just realise the folder named “1” has the same additional line; I just checked now and that folder is also locked, despite having all the permissions and no “locked” checkbox checked, too.

As most of the other folders in that volume are fine, it's not as if the volume was mounted read-only by some kind of software; also, since I can do things using sudo (e.g. I currently have deleted all the half-copied files inside the folder), it's another reason to think the folder isn't “hardware-locked”. The only possibility remaining is a software lock, right?

I tried several utilities (TechTool Pro, Disk Warrior, Disk Utility (Repair disk), as well as the Finder and Path Finder); none of them showed something unusual (other than the resulting fact I can't write to the folder) nor solved the problem.

The volume is formatted HFS+. The source volume was, IIRC, my Time Machine backup disk.

If the software lock is the only remaining possibility, I don't understand why it would have started in the middle of a copy nor why, except the fact that it can't actually write to that folder, no command/GUI item reports something wrong. If it was a directory corruption (on the file system), I would expect both more damages than just a folder being locked and something indicating why the folder is locked (after all, if permissions are right and the folder/volume isn't locked or mounted as read-only, no other property of a HFS+ file system object can lock a directory, right?).

Searching using Google, I can't find other pages than basic ones (about the “Locked” checkbox or the permissions). I'm really interested in understanding what's going on.

What can be that mystery? What else can I try?