You could try clicking on the
View site information button to the left of the URL to see cookies.
Example (you might not see all of them – the locale and theme cookies seem used only if needed):
You can remove one by one to see the page change (do on purpose what might occur when unwanted).
Selective cookie removal like that seems strange, but first see if you’re experiencing cookie removal at all.
Is it fine if Chrome is restarted, but Windows is not? I don’t know why a restart would delete more cookies.
Is Duplicati accessed by
localhost:8200 URL? You can look at its cookie values without Duplicati in use: