How to restore a kup backup ?

I have created a backup using the kde built-in backup tool (kup).
The way to create was pretty straightforward: went to kde configuration panel, backup section, fill the form and done.
Now, I want to restore it. I go to the same place and it shows a panel with an entry to my last backup with a red badge and a white cross (or a big X). Uhmm...

At the bottom of this panel, the "restore" button is disabled...

The backup disk is mounted and looks like there a a big file there:
Code:miguel@fenix:~/tmp$ du /media/miguel/InternalBackup/kup-backup/miguel/
4 /media/miguel/InternalBackup/kup-backup/miguel/refs/tags
8 /media/miguel/InternalBackup/kup-backup/miguel/refs/heads
16 /media/miguel/InternalBackup/kup-backup/miguel/refs
52 /media/miguel/InternalBackup/kup-backup/miguel/hooks
4 /media/miguel/InternalBackup/kup-backup/miguel/branches
8 /media/miguel/InternalBackup/kup-backup/miguel/info
8 /media/miguel/InternalBackup/kup-backup/miguel/logs/refs/heads
12 /media/miguel/InternalBackup/kup-backup/miguel/logs/refs
16 /media/miguel/InternalBackup/kup-backup/miguel/logs
4 /media/miguel/InternalBackup/kup-backup/miguel/objects/info
47201736 /media/miguel/InternalBackup/kup-backup/miguel/objects/pack
47201744 /media/miguel/InternalBackup/kup-backup/miguel/objects
47321876 /media/miguel/InternalBackup/kup-backup/miguel/
miguel@fenix:~/tmp$What is wrong ? Why the red badge ?

Running KUbuntu 19.04.