Webmin Filesystem backup | Restoration complete without errors, but doesn't works

I am using the "Filesystem Backup" from Webmin, but this recovering system doesn't works on my server.

Here my config :

• Debian 10 (Buster)
• Webmin version 1.970

And here, what i've done :

1. Backup creation
2. Manual modification of a file to create a difference between my backup version and the post-backup version.
3. Restoring the backup : the action log tells me that the restoration is complete.

But when I go to see my files, nothing has moved.

I don't know where to go to see if there is any error, I don't know where it could come from ... any idea?

Thank you in advance.