This is the first time I used this tool and loved it on the first sight, despite using it on my local drives. Once I verify the correct functionality I am ready to be a little bolder.
Thank you @drwtsn32 and @ts678 for trying to help me. It was the explanation you need to go back to your Duplicati install web interface (being http://localhost:8200/ngax/index.html#/about) that made me connect the dots.
Here is the warning that I now know how to find, but still cannot understand:
Failed while executing "RepairUpdate" with id: c59b72aa-3777-4b16-a3f1-2efced21f097
My trial of duplicati was simple:
backup to the external hard disk, folder backup
restore that backup to a parallel folder restored-backup
compare the restored-backup with the original folder.
Grateful for this post. I spent an hour slugging through logs trying to find it. I found this link and discovered the warning was failed SMTP credentials.
Feature request, that it could be integrated with the job report SHOW button or at least a link to check system logs so the error is easier to find.