@dalias @liaizon No, the authorization URI resolves correctly so there is nothing wrong with Liaizon's post and nothing an edit would do. The verification is between our respective servers and piefed.zip. Unless that server was coincidentally down at the moment our servers received the post, the reason is something else.
The quoting server receives an Accept activity directly from the origin, everyone else checks the authorization URI. I think it's some failure to ingest the auth object.