In a generated report, if I click on something contained in a combined fragment of a sequence diagram, I get a "file not
found" error from the browser. I checked the report files, and they were really missing.

Funnily, in the "Combined Fragment Summary" of the generated report, only the combined fragments on the outmost level
(excluding nested ones) are listed. So the nested ones were apparently forgotten by the generation process. In the
diagram itself, HTML links to them appear to be present, which results in file not found.