If you have a lot of files making up that 10G of source data, you might be experiencing the “final file” upload issue mentioned here:
Though two hours is pretty long…
If you go to the “Processes” tab of Task Manager (ctrl+shift+escape) and find the “Duplicati.Server” row, is there any activity in the Network column?
Alternatively, you could go to the “Performance” tab, click the “Open Resource Monitor” link (near the bottom), and check out the Network tab in the Resource Monitor window.
I’m not sure what should be showing in the Duplicati logs during this step, but you could also check the main main “Show Log” page and select the “Live” button then the “Profiling” option to see what the most recent commands were.