Restore attempt - Can’t get past Select Files → Waiting for task to begin looks similar. That solution:
Issue was user error related to the encryption passphrase.
Aside from the language, is your screen seen there, basically doing Direct restore from files?
Restoring files if your Duplicati installation is lost is when you do that (more slowly, with more setup).
Restoring files from a backup is a more normal way (option 3 above, and option 1 should be similar).
Restore data from backup archives is a similar case, with some user issues, but solution is not clear.
Duplicati hangs after backup attempt (OSX) Was: Crashplan Refugee can’t get Duplicati to restore
Do you see any similarities of OS, screens, or steps with any of those? That’s all a search could find.