Process Monitor can maybe give you a bit more insight into what the process is doing, e.g. is it using the disk or network? Task Manager can do a bit of that on Process tab, but small actions might not be visible.
For a close look at the network (f the network is involved), there’s Wireshark, and for a simpler peek, you might be able to see whether Duplicati is looking up some hostname in DNS, preparing to connect there:
DNS Caching and How It Makes Your Internet Better
For a heavy C# debug examination, use a debugger.