yes @gianlucabertaina there are some steps in this post on the same error: Fatal error: Detected non-empty blocksets with no associated blocks - #6 by johnvk. I and another user have followed them and got similar results. No precise filenames but filenames “nearby”. Doesn’t lead to a fix, tho, just more clarity around the circumstances of what is looking like a bug in Duplicati.
It would be great to have a third set of results from these steps, if you have the time.