Another user @mdwyer had a similar sounding issue in his thread from the other day, found here. It looks like he was eventually able to work out a solution though it looks like it was surprisingly convoluted to accomplish.
I’m still waiting on the devs (paging @kenkendk) to weigh in on his issue - especially when I went to test doing a “headless” restore from my own backup files as found on Google Drive, I had a nearly identical issue. My suspicion is that Duplicati is making some sort of false assumptions about files contained in the backup along the way for some reason, but I franky don’t know enough about the internals to make a judgment.