I need to investigate, but at the same time, I see your volume is now mounted. Did it mount "normally", or, with a warning that it was damaged and mounted read only?
@softraid-support It always mount with the read-only warning, and it is effectively in read-only, which is my main problem.
That is the problem cause I was looking for.
A volume must mount "read write" (be undamaged) to rebuild.
Disk Warrior is your friend here, its a commercial app, but will fix this.
Alternatively, backup/restore is the free option. MacOS does not have the ability to repair volume directory issues.
@softraid-support Understood. I own DiskWarrior. Can you briefly guide me into the process ?
Great!
Run Disk Warrior, scan the volume. At the end, click "Preview", not replace. Scan through your files, open a few. If you are happy, then "Replace" the directory. Make sure you updated to the latest version.
I still run Disk Warrior at least monthly on every HFS volume I have.

