Restore site does not work

Hey there,
I currently migrated my page from one host to another. So I made a backup to restore the site content after migrating. I can import the backup I made but the restoring does not work. When I click on the green restore button (as shown in our examples in the help section), a loading sign appears for maybe one second and then nothing happens…
I would be so thankful for your help.

Kind regards,
Nike