What value did you use for the setting: SHOW_USED_FILES
Furthermore:

• Can you please attach a, small, self contained example (source+configuration file in a, compressed, tar or zip file!) that allows us to reproduce the problem?
  Please don't add external links as they might not be persistent (also references to GitHub repositories are considered non persistent).
• Please also specify the full doxygen version used (doxygen -v).

Hey @albert-github, you were totally right, I was totally wrong.
I had SHOW_USED_FILES=NO, which after swapping into YES got the exact information I was looking for.
Very useful. Thank you so much!