After upgrading to version 4.7.2, all customized, AND the IPS Default, themes show the [Change Author] button again.
I wonder, if it is not related to the browser one uses: as I did not have to change any author, I admit that I did not pay attention to the plugin, after upgrading my browser, i.e. Portable version of Firefox NIGHTLY v101.0a1.
Maybe it was already working again before upgrading the Invision Community software?